Took the kids to see this over the weekend. I give it a "meh" 2 stars. It's not as horrific as sitting through a Pokemon movie, but it's nothing special for adults to seek out like Wall-E.
Basically it's Lion King lite as the Madagascar crew crash lands in the African reserve where Alex the lion (Ben Stiller) was captured as a cub. All through the movie it was bugging me that I almost recognized the voice of his father. It was Bernie Mac in one of his last performances before his death. The Scar character is played by Alec Baldwin which amused me no end. Kids aren't going to get the gay "let the kid be himself and dance" subtext in full, but I appreciated the message. It just didn't have that great of a vehicle -- this is no Billy Elliot, either. Not worth your $9 if you're an adult without kids.