It is pretty cringe-worthy a lot of the time, so if you like that kind of humour... I sometimes find it unbearable to watch, but for Canadian TV it isn't horrible.
This is my brother-in-law's favourite show. But he's a junior high teacher and he has a different sense of humour than I have so I've never given it a thought. I may have to take a look.
My wife is a teacher as well and loves it. The few episodes I've watch have been really funny. I'm not usually a fan of embarrassment jokes but he makes them work.