Scott Pilgrim and Watchmen both suffer from the quaint notion that a comic book film has to look like a comic book, which is sort of like saying the adaptation of a novel should look like a bunch of words on a printed page.
OK, hyperbole, but still...
SP is all over cable right now, and I leave it on now and again to catch favorite bits (and it has plenty-- Evans and Routh never fail to crack me up), but at no time does Wright seem to be rethinking the material in a filmic context (apart from the questionable change where the character of Ramona goes from intriguing half-fantasy in the comic to drippy wet noodle onscreen). It was likely doomed from the moment it was decided that all seven Evil Exes needed to be crammed into one film (it's a dense 7-volume comic series), leaving no time for anything but amusing setpieces. Granted, there are all too few films with as many amusing setpieces as SP does have, but it's not anything resembling a fulfilling viewing experience for me. Though I'm tempted to say that if they'd found five extra minutes to squeeze Knives' dad into the movie that would have come close to swaying me.
As for Watchmen, again it began with a conceptual dead end: taking Watchmen out of its comic environment should have necessitated completely rethinking it, since so much of its strength is dependent on things that are unique to its original medium. I know that there is some sense that Snyder's trying for a similar meta-commentary on the superhero film, but not only does he never commit to the idea (since he still composes so much of it as slavish re-creation of the comic panels), it's not much of an idea in the first place: the "superhero" film is really just a subset of the giant blockbuster action movie, a topic which seems to me hardly in need of any kind of deconstruction (Michael Bay pretty much does that every time he makes a movie). Like Scott Pilgrim, there are bits of Watchmen that I can enjoy here and there, and I'm probably going to trade in a DVD at Best Buy to pick up the Blu-ray for cheap, but I can't think of it as anything but a failure. FWIW, when I first read the comics, the guy I thought could have done something with the story was William Friedkin: a New York that felt as grungy as Popeye Doyle's, with the more "fantastic" elements having the oppressive ugliness of The Exorcist.
Comic books (graphic novels, sequential fiction, whatever) may resemble movie storyboards, but they're not the same thing. I'm not surprised that Snyder didn't realize that, but I'm surprised that Wright didn't seem to, either.