The one thing that always stands out to me when re-watching Season 2 is the caliber of voice acting. Between Bart Gets an "F", Bart vs. Thanksgiving, One Fish, Two Fish, Blowfish, Blue Fish and Lisa's Substitute this cast is acting their asses off.
I've gone so far as to simply listen to some of these episodes that I've watched over a dozen times without the visuals just to focus on the quality of dialogue. It's scary good.
The comedy gets better in later Classic era seasons as the show finds its form but I'm not sure the acting standard set here has ever been matched in the 26 years that followed.