This was (dare I say) perfect in the comic book movie genre. I absolutely loved all the characters especially Dr. Manhattan. There was a scene that certainly is not intended for children's eyes, but its not over the top, meaning I have seen worst graphic scenes in Indiana Jones, notably the villains death scenes at the end of each.
They stayed true to the comics and I love the universe they created with Nixon in his 5th term in office, etc.
There are a lot of flashbacks and I think flashbacks within flashbacks but its all good, it wasn't confusing to me and flashbacks within flashbacks can be very confusing if done wrong. The director did a great job wielding the story lines together in 3 1/2 hours. Superb visuals and a fantastic storyline, I was a little upset at the end of what happened to one of the characters, but hey can't have everything.
I would recommend this to anyone who loves comic book movies, however this isn't like your normal comic book movies, as it is grittier and darker then most (think of Sin City or 300). It takes the genre in a different direction much like how Chris Nolan did with the recent installments of Batman (which I also love).
The movie deals with current themes in our world today and for that I think this makes the movie timeless. I certainly can't think of why all the hatred for this movie. Not only did it completely stay true to the original comic, but it did this in such stylized fashion. I have decided that Zack Snyder can do no wrong.
I think most people didn't like this because they thought it was boring. Well if a good story must have non-stop action then this and most movies are not for you. There is great action, yes, but there is also depth to the mythology of the Watchmen world.