Well, this season is hit or miss. The episodes are either really good, or terrible. Some are just okay though, like this one.
American History X-cellent: When Mr. Burns goes to jail for stolen artwork, Smithers is left in charge.
There are many funny parts in this episode, like the warden being addicted to helium, or Mr. Burn's huge inmate. I didn't really like how Homer took advantage of Smithers though. But, that's what Homer does.
The B plot was okay. Bart and Lisa raising an ant farm isn't that creative, but there are clever jokes like when Homer thought Patty and Selma died, or when Santa's Little Helper ate the ants.