If you have even a remote interest in the "crime-drama" genre of movie, then stop reading and go see this movie asap. That is, of course, if you haven't seen it already.
Many people have mentioned Heath Ledger's performance as the Joker, and at the risk of beating a dead horse, I will as well. I simply cannot adequately convey, with the English language, how incredible he was. I have seen the movie twice now, and both times I couldn't wait between scenes until the Joker's face appeared again. For any Heath Ledger fan, this movie is a must, and even for those who have very little idea of who he is, you are in for a treat. This kind of performance only happens every few years or so; go see it.