James Walcott links to a nice post about the cinema of Brian DePalma at a website called "girlish." It's very well thought-out, almost poetic - definitely worth a read, even if you don't think DePalma is all that great.
For myself, I used to be a huge fan, but I think his more recent work has gone downhill. He may be one of those artists who has said everything he has to say. If you're a musician, you can get away with that by just continuing to perform your old hits. If you're a filmmaker, you've got to hope you can find good projects that will supply the inspiration you no longer have. DePalma use to write most if not all of his own movies, but now it's pretty rare to see him working from one of his own scripts.
Oh well, his old work is great - much better than he is given credit for. People always accused him of ripping of Hitchcock, but that was mostly because Hitchcock is one of the few filmmakers who is a household word. Many other filmmakers borrow from old movies (as George Lucas borrowed from Akira Kurosaw when he made STAR WARS), but people don't notice it.
Anyway, read the post...