All shows (or at least a lot of them) seem compelled to do a Rashomon style episode sooner or later. There's just something about the idea of seeing things through the perspective of other characters and seeing the difference in how everybody sees things that makes for compelling television. I wouldn't say this episode of Community is exactly a "Rashomon" style episode, but it's certainly close in the way we get six different stories that are similar but have very subtle differences throughout that lead to very different conclusions. Think of it as Fringe and Rashomon's odd offspring.
Each of the six different timelines zoom by in about two or three minutes, and each one, while similar in some ways, end up in very different places. There's some similarities (Jeff banging his head, Jeff turning down Britta's singing, Troy being freaked out over the troll, Abed sort of flitting around the edges, Britta getting high), but as we get closer and closer to the real timeline, it becomes clear that Jeff is the culprit that's tearing them all apart. When he's the one who goes and gets the pizza, people get along. It leads into an incredibly touching ending that is sad in a way; the way Jeff stands off to the side, watching everybody else have fun... I know Jeff can be a "crafty jack-rabbit," as Annie says, but I still feel bad for the guy.
I'm not just rating the episode high because it was a "concept episode." It was legitimately funny as well. The scene where Troy sees the troll sitting in the ring of fire was incredible (in fact, that whole evil timeline was great even if it was a bit too absurd). Britta has continued to be the dark horse of the season, moving out of her comfort zone for the last few episodes. I still think Shirley doesn't get enough to do and it was nice to get a break from Chang here.
Overall, the episode was nearly a bottle episode, with them never leaving the apartment. And we all know this show does bottle episodes perfectly. For me, this was the first classic of Season 3.