One of the better Treehouses in a while. The Zombie Apocalypse in particular is one of the funnier bits the show's done in a long time. For this year:
Act I: Bart and Lisa agree to "solve" each other's teacher problem. CRISS-CROSS! Act II: Krusty's mad cow burger brings about the Zombie Apocalypse. Act III: Homer impales himself on Moe's brewer, giving blood-soaked beer an aphrodisiac effect on Marge.
The "CRISS-CROSS" stuff was pretty good, especially once Willie got in on it. The idea that the last act was done in a theater setting was a neat one in theory, but didn't quite lead to as much funny as I thought it would. Overall, a decent romp, as is normally the case with Treehouse.
I just got back from IM3 and thought it was better than 2 but not even close to 1. The problem they have is IM1 was almost perfect. Everything about that movie, to me, was spot on. The bar is so high that no sequel will ever come close.