Time Out says
They popped up as supporting characters in 2004’s ‘Mean Girls’, which Fey scripted, and now share top billing in the temperate comedy ‘Baby Mama’, with Fey as Kate Holbrook, a child-craving career woman in her late thirties who, after discovering she can’t conceive, hires ne’er-do-well Angie (Poehler) to do the job. When Angie falls out with her slack-jawed yokel of a mate (Dax Shepard, in ‘Idiocracy’ mode), the surrogate-to-be naturally moves in with Kate, cueing much nutrition- and hygiene-based humour.
Written and directed by Michael McCullers, ‘Baby Mama’ is built not on a plot so much as a series of set pieces, and it’s not nearly as interested in satirising its available targets (the baby-industrial complex foremost among them) as one might expect. It’s at heart a gentle odd-couple comedy, and as such, it suffers from the fact that Kate and Angie never emerge as fully fledged characters. Kate is just another variation on the established Tina Fey persona (droll, highly-strung, decent), and while Poehler can be a fascinating performer (she comes in the same flavours as her lemon-chiffon dye job: sweet-sour and impish, and chilly and extreme), here she’s just a blank slate with great timing.