They finally let go of trying to come up with plots and drama like pixar films and focused on the FUN. This sort of espectacle is what kids are missing in movies these days. Good jokes, funny characters and lot's to look at. It's kind of a cross breeding of the Willie E Coyotte show with a Fellini movie.
The circus scene in itself is worth the price of admission. The first film focused more on manic and anarchic possibilities, while the second was deeper and more sentimental. The third is a nice blend of both, colorful, kinetic, and light-hearted fun.
Enhanced by some of the weirdest choices I've ever seen in animation, Madagascar 3 seems to have been fueled by drugs by the guys behind the cameras. It has the potential to become a cult classic at that level.