Rating: Awesome
It was a very, very well-made movie with an interesting narrative technique that I hope to God does not become a popular trope to imitate. I'm glad movies are moving beyond the stage-play narrative structure, with complete scenes followed by complete scenes etc. There's nothing bad about that, but you can do other stuff with movies and it's nice to see them being tried by mainstream vehicles. I would not, however, want to see the hyperkinetic stream-of-consciousness pastiche become the standard. It's nice for a change, but it would rapidly grow wearing.
Michael Cera was not the right choice for Scott Pilgrim, alas. He does a good job, but on several occasions he just missed the tone, even of the script of the movie. He was more "What do I do now?" when the character seemed to be written to be more "What did I just do?" Scott Pilgrim appeared to me (without knowing anything about the comics) to be an act-now-think-later character, and Michael Cera just cannot get away from his neurotic worrying mode of behavior.
Other than that (and as I said, he does a good job for the most part) the movie was just a delightful psychedelic romp well worth paying to see in the theater, where the surround sound and enormous screen can let you bathe in chaotic sound and light for a while.