If I could distill Cera's performance in this film (or at least from what I've seen within the trailer) to a single term, and it's the basically the same word I'd use to describe most of his roles, it'd have to be awkward. He never seems to evolve past the character prior to his hooking up with Ramona; Cera's portrayal lacks the subtle confidence, charming goofiness, and is simply without the overall "Cool" factor of the Scott Pilgrim from the graphic novel.
The character is by no means a debonair but he's certainly not an unattractive, frail individual with a awkwardly reserved personality. He's supposed to be the best fighter in his province for God's sake, you expect me to believe that Michael Cera's bony ass is capable of anything beyond getting his ass kicked? Not only does Cera's performance not embody the character's personality, but he simply does not look the part. He seems incapable of being awesome, which is a HUGE problem for me, considering the fact that these types of moments are a staple of the character in question.