It's almost odd that it could be a question at all, isn't it? Everyone who read this book seems to have come away with a rather firm opinion on Draco's characterization, myself included. Yet in the month since the release of HBP, I have heard solid arguments for nearly every interpretation of Draco's character. This kid has had a multitude of charges levelled at him after his role in Hogwarts' invasion: "he's a coward/ he's a victim/ he's a total Death Eater-in-training!" And of course there are more (the werewolf theory, etc.), but these three seem to be the most frequent and central accusations that might determine Draco's activity in the series at a later date.
So all three should be examined carefully, right?
I myself was initially surprised to see and hear Draco labelled as a coward in book six. My instinctive reaction was: "So...not killing an unarmed, old man who is up against the wall is cowardly now?" Yet this is an uncommonly popular theory (Draco's cowardice, not his final actions in the book), and has been argued efficiently. The main argument does not focus on Draco's inability to kill Dumbledore at the end, so much as it does on his two previous attempts to kill Dumbledore from afar, which indicate only a reluctance to kill Dumbledore face to face, with his own wand. This, perhaps, is where the subject of intent comes into important play. For those who have long felt that incompetence and sabotage pale in the face of intent, chances are that they are also those have found Harry's intentional casting of the Cruciatus and/or Sectumsempra curse unforgivable, as inability to effectively cast the curse does not forgive the initial intent to do so. Chances are also that they have long been set against Draco and/or the Slytherins, since PoA: for example, the Dementor scheme during the Gryffindor-Ravenclaw match was a flop at best, but as the entire school knew only that Harry fainted at the sight of Dementors, their intent was arguably to make Harry fall over fifty feet off of his broom, and all the Patronuses (Patroni?) and detentions in the world cannot change that. Somewhat similar to both cases mentioned, you do not send a cursed necklace or a poisoned bottle of mead out into a school without some intent to kill. The incompetence of said schemes, or the failing of them only through pure luck, does not negate this intent; yet the intent can easily suggest that Draco found the idea of killing from afar more comfortable (and I use this term very loosely, since Draco appeared very uncomfortable all year round) than doing so up close: if the plans had succeeded, then their succuess could be put down to pure chance just as obviously as the foiling of both plans have been -- and in this case, Draco would have been comparatively less to blame. It is a similar minset that compels Draco to let the Death Eaters into the castle, as is revealed in the Astronomy Tower (if the curse that kills Dumbledore does not come from his own wand, he is again, comparatively less to blame); and this is the core of the "coward" argument. He had the intent to kill, only he lost his nerve when it came down to actually doing so himself.
But valid or not, is this a reasonable, or fair argument to make? For one thing, it has little bearing on Draco's future, imo (since whatever illusions Draco may have held throughout the book, the events at the end have obviously destroyed them). And for another, I have found that it mostly disregards the reasons behind his actions. So the subject of motivation enters into the equation. Motivation behind the action has always been a huge and important theme in these books. It is what makes all of the characters in the Potterverse appear grey at some point or another. Rowling is very careful to describe Narcissa's overwhelming distress over the fate of her only son, before she places Snape under a binding contract that basically forces him to choose between Dumbledore's death or his own. Snape himself remains as ambiguous as ever, even after having killed the Head of the Order, because the reasons behind his actions are anybody's guess. Even the fact that Draco nearly killed his best friend has not yet registered to Harry, because he is still dwelling on the motive behind Draco's actions. Readers have been shown repeatedly that motivation is something important to consider when judging the actions of the HP characters. Yes, maybe delusions of grandeur and desire for revenge in the name of his father were part of what made Draco accept Voldemort's mission in the first place. But I think it's been universally agreed on that, however Draco handled his situation, he was in way over his head; and what made him hold to his assignment is the bargaining chip that the Order claims Voldemort has long used to retain the loyalty of his followers (OotP, p. 90): blackmail. In this case, threat of death to Draco's entire family. Draco is by no means the first to have been trapped in this manner; evidence suggests that Regulus Black was similarly trapped. These are sympathizable circumstances in any case, in spite of his actions. None of this makes Draco a fallen angel, but it does define him very clearly as a victim in this book. This perspective is supported by canon, and is one that those who take the subject of motivation into high consideration when studying a character's behaviour, are likely to adopt.
Yet at the same time, some might feel that, motivations and even intent aside, it is the final outcome of their actions that a character must be held accountable for, and is therefore the most important thing to be considered, because of the others who have to deal with the consequences of said actions. This is an equally valid perspective that has been applied to many characters by readers over the course of the series. Everything else aside, Hagrid would (should?) have had to explain to an irate Lucius Malfoy why Draco was attacked by one of his beasts. All other issues aside, it was Mrses Crabbe, Goyle and Malfoy who had to find their sons in slug-form, at the hands of the D.A., once the Hogwarts Express reached London following the fifth-year; and Harry who canonically HAS been held fully accountable for Narcissa's son being slashed across the chest in sixth year. Snape and Remus, too, were the ones who had to deal with the aftereffects of Sirius's Prank. There are many who feel that final outcome is equally as important as motivation, if not more so; chances are that they are also those who find it easy to view Draco as a villain in the sixth book, for the total sum of his actions, if viewed as actions only, are quite frankly unforgivable. At the end of the day, both Katie Bell and her family deserve to know why she spent over half of her N.E.W.T. year in St. Mungo's, whether or not Draco felt that sending a cursed necklace was a serious attempt to end Dumbledore's life (as has been popularly suggested in the fandom, it IS possible that Draco himself did not expect his murder attempts to work). Similarly, it is both Mrs. Weasley and Fleur Delacour who may or may not be interested in the details surrounding the reasons why her son/fiance is part-werewolf now. Madam Rosmerta may also wonder why at least a year of her life was spent under the Imperius curse, presumably cast by Draco (we are given not even a hint of any Death Eater who may have been in the Hogsmeade vicinity for that long without drawing suspicious, with the exception of Snape, who we are told had no inkling of Draco's plans).
The villain!Draco perspective is supported in canon just as strongly as the previous two theories are. Simply put, Draco is dangerous in this book: he does not care how many people he might knock off to get to Dumbledore, until (presumably) after the fact. It is he who gave the honorary end-of-book "villain's confession". The consequences of his actions are being, and still do have to be dealt with by the victims, regardless of Draco's reasons for them. Fear does not change or undermine his responsibility for his actions. Draco is no longer merely a badly-brought-up little boy with nothing to atone for; Lucius Malfoy is not seen as "more innocent" for giving a little girl a murderous diary and loosing a weapon on the school, simply because (again, through pure luck) no one was killed and there was no lasting damange done -- and Draco was not as lucky as he was.
So, these are the three main mindsets that I have found to go along with these three popular definitions of Draco's HBP-character; most arguments seem to orbit around the subject of either of the three. I suppose that personal perspective really depends on whether you take intent, motivation, or the actions themselves into the highest consideration when studying a character's behaviour. Of course, it is possible to hold all three in equal consideration at once, and is probably best: this is how the character becomes extremely ambiguous (ie, Snape). However, I also think (in this case anyway) differing perspectives occur because everyone hahs their own system of what to take into account when passing judgement on a character. Then, what does this spell for Draco's fate in book seven?
The following is based completely on my own reading of the text now, but also on purely factual points. I have to say that I can't see Drao becoming (or, debatably, continuing to be) a Death eater, no matter how his character is perceived. We know for a fact that Voldemort basically set Draco onto a suicide mission: he was merely a tool to be used in Voldemort's revenge against Lucius. There was not meant to be any way for Draco to win, Narcissa made this clear; either he would be killed in his attempts to murder Dumbledore, or he would falter, in which case Voldemort would kill him. We know for a fact that Draco did, in fact, fail in his ultimate mission, and there were at least four other Death Eaters present to bear witness. With this in mind, even if Draco is perceived as a victim motivated by the threat to his family, the chances of him remaining a Death Eater are slim. For one thing, he made the conscious decision not to kill Dumbledore even with the threat of death hanging over his head. For another, if after only one year (or less) Voldemort is already forced to use the threat of death to his family to keep Draco's loyalty, then Draco is the least loyal Death Eater (or Death Eater-in-training) that we've seen in canon; and Voldemort knows it. And the events on top of the Astronomy Tower would only confirm this further.
And if Draco is instead perceived as a villain, then his chances of remaining a Death Eater are even slimmer than ever; for this only makes the lowering of his wand all the more poignant. His turning away from the assignment that he has steadfastedly followed year-round is made that much more significant: because lowering his wand is not only a conscious decision not to kill Dumbledore, but a decision to end the assignment right there. To stop listening -- stop following -- Voldemort's orders. Which, of course, is not a great start for any Death Eater.
As for my own perspective out of the three? Having never been interested in Draco prior to HBP, I think I'll have to wait for feedback from other readers to get a truly fair perspective. The motivational aspect won out on the first reading, maybe by default (I have always found the Weasley twins' behaviour easier to forgive when their motivations are admirable). I can't say I'm any more interested in him post-HBP than I was before, but contrary to popular belief, he did finally get his very own story, and I have to be rather impressed by that. I also have to note that there is at least a two-year wait for me to gain a fair perspective (since I'm sure the two years will be chock-filled with theories), but no solid conclusion about Draco's character and future, except for what I do know.
He really is very clever, to not only outsmart Dumbledore, but also one-up Voldemort (who has never been able to get more than one Death Eater at a time into Hogwarts). He is Harry's equal schoolyard antithesis after all -- I wondered after OotP, but I'm fairly sure now. seeing as he has yet to lose in a one-on-one battle with Harry in which Harry knew exactly what he was doing, though he has won one-on-one, where he knew exactly what he was doing. I have to admit that I did like the warped sort of parallel between Harry, Draco, and their mentors/father-figures in the last two books: Harry wanting help and attention in OotP while Dumbledore withheld both; and Snape offering help and attention in HBP while Draco refused both. And I'm not even close to being an H/D fan.
I know he (Draco) is in a lot of hot water right now, but that he has definitely become a formidable character. And I guess all else is theory.
I'm also wondering why sixth-year students are casting Unforgivable curses all over the place and not even being called upon by the Ministry of Magic; but again, theory.
This is also posted in my own LJ.