As I said in Eltopo's thread, I loved it, it wasn't perfect, but it was as close to Watchmen as we'd ever get.
I actually think a lot of the changes made were appropriate and served to make the story fit better on film. The understated fight scenes may work well on the page, but on screen, you can do more action in a shorter space of time, and Snyder took advantage of this, the action was breathtaking, and I liked the 'slow it down, speed it up' approach, it makes you feel every punch. But I'm not sure it will work as well on dvd, 300 was amazing on the big screen, but on dvd, not as good, you need the big picture to get into this sort of action.
The movie also put the political, cold war stuff more to the forefront, and I liked that, in the book I didn't get the sense that nuclear war was possible at any time, but the movie made sure I did (although Nixon was bizarre, a cartoon, they might as well have got Billy West harrroooo!) The ending was also a good change, it made sense in the context of the movie, and the Squid would have taken too much set up, plus if you look closely, the anagram for the Machine Veidt had is S.Q.U.I.D.
I thought the acting was strong, I don't have the same problems most of you do with Akerman as Silk Spectre, I think she did OK with what she had, which wasn't as much as the other characters, her and Ozymandias didn't have enough scenes, we didn't get to se Veidt as a hero, it was too obvious he was the villain, but Haley was amazing as Rorschach, just straight off the page, as was Wilson as Nite Owl. Morgan was good as the Comedian, but didn't have enough scenes in my eyes. Crudup had a difficult job, and I'm not sure whether I liked it or not yet, but he was impressive at getting emotion across through all the cgi.
Just brilliant fun, I can't wait to see it again.