My problem with the Watchmen film wasn't what it changed, not directly. My problem with it came as a result of some of those changes and more importantly, because of the changes of the medium. My problem was simply this: It watered down the message and characters. Let me throw down an example before MovieBob tears my head off (AWOOOOOGA, MASSIVE SPOILERS OFF THE PORT BOW):
In both the comic and the movie, the final moments of Rorschach are taken as he heads off to go warn the world of what had happened, forsaking world peace for his own sense of right and wrong. Dr. Manhattan comes out to stop him. So far so good, right?
In the comic however, there is no commentary from Rorschach on the morals of it, no Nite Owl. He simply tears off his mask, crying for the first time since we saw him cry in flashback and screams at Dr. Manhattan to just do it. Meanwhile, Nite Owl is upstairs sleeping with Silk Specter. It was a HEARTBREAKING moment, precisely because of the subtleties of the moment.
In the movie however, he gives some half-assed lecture to Dr. Manhattan about how this is his fault, and when Dr. Manhattan does it, Nite Owl drops to his knees screaming and gives another half-assed lecture and I was sitting there wondering how Zack had managed to ruin the most moving scene in the comic.
I'm still not sure where I stand on the Watchmen movie. It wasn't the generic action-flick that was League of Extraordinary Gentlemen film, nor did it's point, story, characters and themes get quite as neutered as in V for Vendetta (a okay enough film on it's own, but when compared to the comic, it's pathetic). I guess they did as well as they could with a Watchmen film...
I also guess that's not good enough.