The mediums of comic and film are different. You can do different things with them, and you are allowed to get away with aspects in one which wouldn't go in the other. There are obvious ones, like you can have sound in film. You can have motion in film. The comic medium does have some philosophical advantages, but one advantage is also a con - the comic medium is more forgiving with limited plot. Although the film medium is younger, its narrative has developed much more rapidly, which is why, though the visuals of Sin City translated near perfectly from one medium to the other, the dialogue and plot was not nearly so successful.
I have no problems with a movie being a movie instead of trying to be a comic book. An adaptation should be trying to be great for its current medium, not the old medium. This is true whatever the old or new arena is, including opera, stage, novels, poems, songs or albums. Sometimes the versions will be facially similar (like Chicago), and sometimes they will not be (Blade Runner versus Do Androids Dream of Electric Sheep).
That Watchmen not only came out as a great adaptation but a good movie as well is a nod to all of the people involved in this project, especially the writers and director, and I suppose the producers as well. It was a slam dunk all around.
To briefly summarize for the few unfamiliar, Watchmen is a film set in 1985 in an alternative universe. It's a world where costumed vigilantes similar to Batman and The Green Hornet roamed the streets, and a super-powered man named Dr. Manhattan altered the course of history. The United States won the Vietnam War, term limits were changed to allow Richard Nixon to remain in office, and non-sanctioned vigilantes were officially outlawed in the 1970s. The characters, plot and even much of the dialogue came from the comic book of the same name by Alan Moore and Dave Gibbons.
I'm not going to quibble with the differences between the comic and the movie. The changes worked, they helped the flow of the movie, and there's nothing missing or altered that, if restored, would make the film better. There was a steady pace to the film, with enough plot to keep viewers interested, enough characterization to lend depth, and enough action to maintain entertainment.
The movie was not without flaws, though. For characters that were vigilantes and not superheroes, many of them exhibited superhuman strength and skills. They must drink a lot of milk in that alternate universe, because many of them could punch through walls and survive being thrown into stone without so much as a broken bone. It's also interesting to note that some of these retired heroes had been out of action for nearly a decade, but could still fight off hordes and hordes of bad guys.
The action, though, let it not be said I disliked the action. Note to Christopher Nolan: ask Zack Snyder how to film a fucking fight scene. Clear, concise, energetic, dynamic. You don't need multiple cuts and unnecessary close-ups to hide the action, unless you just don't know how to film two men punching each other.
Yet Watchmen was not an action movie, it was a mystery, a thriller, a drama. You need a solid script to carry such lofty dreams for a comic book movie, and we had just that. My complaint is that most of the back story was satisfactorily explained, but a few modest points were left out - how Bubastis came to be, why Rorschach's mask moved - and some plot points were tossed in that felt off, but these are minor quibbles.
I won't quibble with the romance. Romance in comic book movies often feels stupid or lame. It seems, really, that the best romance for vigilantes may be the awkward ones, which I thought Tim Burton handled well on his Batman run. There's something frail and human about the characters that makes the romance work. Really, though, after so much blue penis, the love scene was my reward. Malin Akerman was a visual delight.
She was not the only feast for the eyes. The costumes were well realized, a good translation from comic to screen, something X-Men will never live down. The cityscapes were engaging without being overwhelming, and the special effects were really top notch.
Overall, I recommend the film. The more it sinks in, the more I like it. It's definitely worth the money, even for IMAX prices, and it stands on its own as a legitimate work of motion picture art. I'm still not sure if Alan Moore would have signed off on Watchmen, but you couldn't ask for a better realization than what we got.