I've been waiting for this movie for at least eighteen years. And I thought it was pretty good. There was a
lot that was left out, yet it was still pretty dense and nearly three hours long. And, as far as I can remember, there was only one major plot point changed, and I think it actually made sense in the context of the movie's limitations, and actually wouldn't have been a bad way to go in the original comic.
(This spoiler contains a spoiler for the comic that isn't revealed in the movie. Caveat lector.)
Having Dr. Manhattan be the fake attacker actually makes more sense, I think, but it wouldn't have been able to provide the clues as to who was behind the scheme that the comic's scheme provided. Of course, that leaves the existence of Bubastis as an anomaly.
And I'm pretty sure that Jackie Earle Haley was born to play Rorshach.