I didn't really like the celebrity impersonator episode all that much but I liked the other two so far. Overall, this season has just been ok for me. Definitely the weakest of the three, but that's just my opinion.
There's been a lot of strong episodes thus far, but I really enjoyed the episodes that actually evolved classes. Like the pottery episode, or when Jeff makes up a class, or when Troy lied in drama to fit in. Sure, the school is a great setting, but having dorky adventures isn't enough. I'm happy they've been branching out in terms of setting and story, but I loved it when the classes were tied to the narrative.