Most people I have talked to have not seen this movie. I suggest you do.
Its a classic revenge plot, with a twist. Val Kilmer plays an excellent tweaker with a sense sense of retribution played out beautifully. Now, I know, Val isn't the best actor, but he did his homework in this movie, and played it right.
Vincent D'Onofrio plays an excellet "bad guy" as he does in all of his roles, and is completely out of his gord.
There are a few other B list actors in the movie you'll recognize including Luis Guzman.

Why you should see this movie: The story! Its told very well from the point of view of a meth junkie. The humor is dark, but makes you smile and tugs on your emotions from the getgo. There are no boring spots in the movie, and the directing is superb. Cutscenes and flashbacks are integrated flawlessly, allowing a sense of loss in the moviegoer few movies have the ability to. It ends well with a good solid finish, and not the whole "what the fuck did i just waste the past two hours of my life for?" style that seems to be trending upwards as of late.