For all the interesting ideas, some decent acting, and great special effects, yes, this was an absolutely horrible movie. That being said, I still find myself watching it over and over again. Dunno why, but watching California sink into the sea, Hawaii on fire, Woody acting like... well, Woody Harrelson, Leaders of the free world turn on Platt (who despite the reality of the situation as the only sane person in the room at the time is just so damned dislike-able) makes it a seriously guilty pleasure that I revisit over and over again. But you gotta have some serious suspension of belief (or just a serious history of drug abuse) to be able to sit through it at all. Come to think of it, drugs may be the only reason this made any money at all.
