I loved the Robert Rodriguez and Frank Miller film adaptation of Sin City. It was an aesthetic triumph. I recently re-watched it when Forrest Black and I went clubbing in Portland with DJ Mohawk Adam and Sin City is still fun when re-watching it on a large screen in a goth-industrial nightclub.
Truthfully, the actual comic book Sin City turned me off though. Frank Miller was instrumental in getting me into comics with his Dark Knight re-envisioning of...
When asked if he had seen any of the work that was being done for the Watchmen movie Moore replied, "I'd rather not know."
Moore did sell the rights to his two franchises, From Hell and League Of Extraordinary Gentlemen to be made into movies. He later admitted that was a mistake. "I thought that they could make the movies... and it wouldn't be associated with the comics. I was wrong. I guess I was being very naive." and after that he vowed to never again make movies based on comics that he owns the rights to.
He doesn't own the rights to any of the properties he did for DC, and he didn't have any say in the subsequent movie versions (V for Vendetta, Constantine, Watchmen.) For those movies he wanted his name taken off of the credits and his share of the royalties go to the artists. basically he wants nothing at all to do with DC, and he has also said that he wants the same deal (name removal) for future reprints of his comics that they put out.
I don't really feel that he made a deal with the devil, so to speak. Keep in mind that this was in the early 80's before corporate mergers, before blockbuster movies. and Independent comics were just coming out. I think that anyone, probably now more than ever, that was just starting out in comics would love to be picked up by Marvel or DC. Sure, they might not know what they are getting into, but you can't really fault them for that.