That seems to be a common reaction, but at the same time I'm noticing that people who actually LIKE the ambiguous nature of Lindelof's storytelling (and who embraced the same thing in Lost), seem to be liking the movie a bit more.
Fortunately I'm one of those in the second camp, so hopefully I won't find the movie quite as irritating as others here...
I like the ambiguity and the film is perfectly enjoyable. The stupid parts are no more stupid than the Joker having time to install enough explosives in a hospital on every level without being noticed to make it explode massively or the molestation of some basic laws of physics for the convenience of the story in NuTrek.
Those things irritate me but don't ruin the story completely. My disappointment stems from the fact that I had such high hopes for something less schlocky than this turned out to be. I was hoping for X-Men 2 but got the Wolverine movie.