Films like "Blow" go to show that no matter how much you dress your films up, if the director doesn't fully know his story, then it just can't work.
"Blow" tries to be a lot like "Goodfellas". Both are similiar (narration, soundtrack, Ray Liotta, etc.), but the difference is simple:
Scorsese is a skilled director. Demme (may he rest in peace) was not.
Henry Hill was a real loser. Made Scorsese made us care about what happened to him and his family.
George Jung (sp?) was also a loser, but the film (I felt) couldn't keep the viewer interested. It didn't make the viewer care.
And while Depp is a great actor, I felt this was one of his weakest performance.

Still, "Blow" is an entertaining flick. Not a bad film to watch on TV on a rainy day, but not a great film.