Speaking as an outsider (never read SP, don't care either way about Michael Cera), I found the movie to be moderately entertaining at best. The fight scenes were generally fun, and Kieran Culkin as the gay roommate was probably my favorite character.

However, for at least the first third of the movie, I wanted to punch Cera's character in the face. First of all, dating a high schooler at his age is creepy/loserish, and the way he handled the situation made him out to be a giant tool. Second, what on earth made Ramona Flowers attracted to him in any way whatsoever? He presented himself as a complete loser, and she was built up as this epic awesome hipster chick, and somehow they hooked up? What? Why? Maybe it would have helped if they had an ounce of chemistry together, but if it was there, I sure missed it. Third, all the video games the movie referenced seemed to be about ten years before its audience was born; they all seem to be hardcore for games that they wouldn't have played. (I mean... Sex Bob-omb? Really?) Finally, this movie is targeted at hipsters and retro gamers, which all together do not exactly make for a huge section of the population. So it's not a huge surprise to me that it tanked as hard as it did at the box office.