It's good, yes. And I like that the movie has such a strong music focus.
That said, Rak had some great points. The Sergio Leone westerns have amazing music that stomps all over both Scott Pilgrim and Inception. I can't say I'm a huge fan of Hans Zimmer, honestly. I think some people are still riding the Inception high. Sure, he's good, but it's very similar in style to Jesper Kyd's work, except I think Mr. Kyd is better.
Personally, I think we need to separate and qualify what people mean by "best" music, and what parts of Scott Pilgrim's music we're talking about. Because I enjoyed the way Scott's band was portrayed as actually pretty awful. If you listen to the lyrics and chord progressions/melodies, his band is crap. This becomes more obvious when you compare the lyrics and melody/harmony of his band with something like Clash at Demonhead or the actual soundtrack music.
Don't get me wrong-I loved the movie and I like the music a lot, but the parts of the soundtrack that didn't come from Sex Bob-Omb was superior to the stuff that did. I enjoyed Sex Bob-Omb in kind of an ironic/funny way, since it wasn't really that good (but entertaining), but I can't honestly recommend it. Eh, I do also kinda think indie rock is mostly hack rock, so that opinion could have something to do with why I don't think tracks like "threshold" are all that good (the chorus was okay).
Anyway, my nominee is "Shadow on the Sun" from Collateral. Well, that and pretty much any of the music from that movie, especially the club scene.