It's hit and miss for Sam and Max which means it's still much better than most other adventure games. The main complaint seems to be that each episode is a bit too short -- they generally come in at 3 or 4 hours. But that means over the whole season you get 18-24 hours of gameplay, which is about standard for a point and click adventure these days.
My main gripe with it is the overuse of certain characters and locations. But that's really only a minor gripe. As m0r94n says, it's worth playing the demo because it'll give you a good feel for the kind of humour that's in the game.