Tina Fey and Amy Poehler in Baby MamaBABY MAMA

Despite its sunny, friendly veneer, there's a rather scrappy little war being waged within writer/director Michael McCullers' Baby Mama - one between a lighthearted, pleasant sitcom and a sharper, smarter, more cynical sitcom. (Two and a Half Men versus 30 Rock, as it were.) The former wins, and we could have predicted as much, but the best parts of this engaging buddy flick suggest the truly sparkling comedy it might have been, if only it weren't so eager to be ... well, lighthearted and pleasant.