At one point I found myself thinking "this is staying too frame by frame true to the graphic novel, it needs to breathe its own air" then, thirty seconds later, was pissed that it left out one of my favorite lines from the novel.
A very good movie. Nowhere near its source material, of course.
Don't go expecting a superhero movie - you won't get one. It's more a deconstruction of the superhero myth - what would the world really be like with people like this, and what kind of person would really do this kinda stuff. It's a love letter to and critical evaluation of the superhero all in one. There's a reason Time Magazine said Watchmen was one of the top 100 English language novels written in the 20th century.