All these one-star reviews are absurd - the idea that a film doesn't match your expectations doesn't make it a bad film. It just makes it a surprise.
On its own terms, WATCHMEN has some exceptional performances, grim moments and amazing visuals. It's best to see it on the big screen. Just remember that it's long, epic, strange and complicated. There are some wonderful parts, and some undercooked parts.
I'll bet that this movie gets a lot of people talking and has a long life after its theatrical release as a cult classic.
This movie takes Indiana Jones into the 1950s, in both form and content. I loved it, and already saw it twice. Anyone complaining about how plausible it is should check their heads: how much of what happens in ANY of the other three is particularly plausible? Does the Ark of the Covenant melt faces? Can death cults turn you into a zombie by forcing you to drink blood? Can knights from the Crusades live for centuries guarding a mystical cup of eternal life? I mean, you might THINK so, but logically it's not MORE plausible than what happens in Kingdom of the Crystal Skull.
Go back and watching the other movies and then watch this one. It's, guess what, remarkably similar. I'd rather watch this one that Temple of Doom.