He worked very well for me. That was the first time I saw Matthew Goode in anything and his portrayal had this allure, suave, and cockiness that worked perfectly for the character, IMO. To this day if I see him in anything I can't help but to assume that his character has some ulterior motive.
And the film ending was nearly infinitely better than the comic book ending. The only problem for me was that I had no real connection to the Cold War, so being in more of a post-911 timeframe the nearness to doomsday didn't resonate. I suspect if it came out today though, it would resonate much more.
Regardless, I loved that film - it's probably in my top 3 of comic book films, honestly. The characters of Rorschach and Dr. Manhattan were enough to carry the film and make up for any perceived misses.