In any case, I thought the movie was unique and very enjoyable in many ways, if not exactly deep. A more literary movie, for instance, would have each of Ramona's ex-boyfriends represent something, either about love or about Ramona, but most of the exes are played for laughs.
I thought the comic book series Scott Pilgrim's Precious Little Box Set might have the ability to provide more than the movie's relatively shallow plot.
The verdict: the books do a little better, but not so much better that I would recommend them over the movie. One of the best things about comic books is that they have an unlimited special effects budget, so you would expect the comic book to be even more over the top than the movie. But in many cases, the movies one-ups the books. For instance, the vegan police segment on the movie works way better than what's in the books.
You can read the books in a couple of days (they're comics, each about the size of a Japanese manga). The style is not quite manga-style, though there is a lot of negative space in use, with certain scenes told entirely via pictures rather than with words. The plot is largely the same as the movie, and the characters, while a little bit more fleshed out, aren't vastly different from that in the movie.
I would recommend either watching the movie or reading the books, but don't do both like I did. The movie's a lot shorter, and gets all the highlights of the book right.