Dialogue like "I feel the power flowing through me like an electric current" is what makes The Ninth Gate one of the worst films of all time (especially considering that the line refers to the power of Satan). And unbelievably funny, if you're in the right frame of mind.
It is hard for me to think of any redeeming values in this film, which stars Johnny Depp as Dean Corso, a rare book dealer who knows his occult books as well as he knows Don Quixote. He is recruited by Boris Balkan (Frank Langella) to uncover the mystery of The Nine Gates of the Kingdom of the Shadows, a book purportedly written by the devil himself. Apparently only three copies are in existence, and the authentic copy allows one to conjure up the devil and live forever. As Corso figures out the secret (which takes him way too long), he finds himself in more trouble than he bargained for.
The Ninth Gate is bad for several reasons, but the most striking one is attributable to the horrible script and the dialogue. Depp is okay as Corso and all the other actors are terrible. The settings and set design are decent, but the special effects are nothing to write home about, particularly if you consider the fact that the recent Mission to Mars and Pitch Black were much superior in those terms (and that's not saying much---it has been slim pickings thus far this year). Give me End of Days any day, which at least didn't purport to be high and mighty.
Besides the line I quote above, there are many many pointless scenes in this film that goes on for longer than it should. For example, why include the whole taxicab scene with the turbaned driver going "no problem, sir"? Why have Balkan routinely check up on Corso without any real motivation? What is the role of the French girl who keeps saving Corso? Why bother watching such a waste of time? Unless the point of the movie is to laugh at other cheesy supernatural movies (which I somehow doubt, though it's not inconceivable given director Roman Polanksi's The Fearless Vampire Killers, I highly recommend skipping this one (or watching it simply so you can laugh at it). It would've been more exciting to watch Polanksi try to film this one in the U.S.