I've been thinking of films that have had good premises and have had a lot of potential, but for some reason or other failed in being great, or even good, in some cases. I decided to make a list with a few films I can think of right now. Feel free to add your own in the comments. Here's my list:
Donnie Darko: This film started out good, and got better as the film went on. I loved the idea of a troubled teen seeing a giant disturbing rabbit that tells him to do crazy shit. It had so much potential if it just followed this story line. But noooooo, it has to get all confused with itself by introducing time rifts and time travel that makes no fucking sense. It absolutely drove me nuts.
I am Legend/The Omega Man: I put both of these together because they were based on a great book, but both of them completely got away from what made the book great, and just dumbed it down into lame action flicks. Read the book, then you'll know what I'm talking about.
The Science of Sleep: Now, I have a hard time putting this movie on here, because I genuinely liked it. The idea of a guy who has a difficult time differentiating between what he dreams and reality is done beautifully, but I feel like it was holding back a bit. It is still a great movie, though.
Spider-Man 3: This could have been the best of the all the Spider-Man films. It's fucking Venom, dammit! But nooo, they had to go and throw in like 50 villains, too. This movie was almost unwatchable and made me so very angry.
Sunshine: Let me start this off by saying that I love Danny Boyle. He is a great director and I very much look forward to all of his work, but this film was pretty much a throw away. Now, I have to admit that this was a beautiful looking movie, but it was full of lame Hollywood cliches. My main problem is the near superhuman badguy popping up out of nowhere at inopportune times to artificially move the plot. This could have been a great movie without the villain. The suspense was there even before he was introduced, and was much more genuine.