This episode was pretty funny and even though I wouldn't say that it was "weak" per say, I'd have to say that it was not up to the caliber of what South Park usually is.
"Screw you guys, this season is awesome!" No offense intended... just a joke. I love this season, Fun with Weapons and Wall-Mart are two of the funniest episodes to ever come from Matt and Trey in South Parks 8 year run.