Coming From a Huge Fan of the Comic Series.

Rating: 9/10 (7 January 2012)

When compared to the comic, I'd argue they could have made it longer or split it up into a trilogy to include all that they left out. When viewed as a stand alone film, this is an utterly fantastic film with truly unique Special Effects and Editing.
Story: 8.5/10 I adored the story in the comics, even though it was the character development and dialogue that made the series. As far as the main plot goes, they did it excellently and even the changed ending was equally as good as the book's. My major complaint was that they basically did Scott Pilgrim: Precious Little Life (the first comic) perfectly and it was nearing 1/2 of the movie. But then for the other 5 they chopped out every bit of side plot possible (such as Scott getting a job, the high school flashbacks, and Knive's father trying to kill Scott) and left the bare minimum. All these side stories were equally enjoyable as the main one and were what really developed the characters well.
Acting: 8.5/10 As far as casting went they portrayed all the characters accurately as far as looks go, but there were 3 stand outs for me. I thought Stephen Stills, Scott, and Ramona were played sort of badly. In the comics I saw Stephen as the kind of emotionless guy who didn't care much, but he was played as if he's really nervous. In the books I saw Scott as the obnoxious, annoying, nerdy guy, but Micheal Cera plays him like the quiet and awkward guy. And Ramona was played as if she was a Gothic, emotionless person who didn't ever smile, but in the book she seemed more girly and she was smiling quite frequently. Ramona particularly annoyed me because there weren't any of those happy, funny moments between her and Scott which made more of a reason for Scott to like her.
Special Effects: 10/10 The special effects were the stand out part of this movie. They were probably the greatest comic book effects to date. The editing was flawless with split screens, tracking text, and great fights galore. I was absolutely awestruck by the actions going on on screen. And as far as the first book goes, they basically did it panel for panel and that was truly impressive.
Directing: 9/10 I feel that Edgar Wright truly loves this series, and based on the first 40 minutes, was planning on doing it much more accurately and much more like the books. I think it could have easily been made into a 2 part series (book 1-3 in the 1st, book 4-6 in the 2nd), but they probably ran into time or budget restraints. But from what was made, Edgar did a brilliant job at recreating what he did.
If you haven't read the series, I think you'l love this movie to no end, and if you have read the series you'll love the movie, but will be angry with what they left out. Truly a great movie adaptation that's worth the watch.