A simple buddy cop flick, with the token male leads replaced by two women. That's about all the originality you're getting here, the tone and structure of the film are exactly the same as a billion others, only the jokes are a bit more female-oriented. The result is expected, but not entirely terrible.
Two loner cops, with opposite values, are assigned to each other to solve a case. Ashburn loves to follow the rules and relies on her IQ to solve cases, Mullins does whatever to crack a case open and uses her street smarts to get by. The two hate each other at first, but as they get close to the drug lord they're supposed to catch, they begin to appreciate each other's qualities.
Most of the comedy comes from McCarthy, with Bullock being pretty apt at playing the boring cop. The jokes are never really that funny, and two hours is a bit much for the basic setup. The decent pacing and the commitment to the comedy make it a passable film, just keep your expectations to a minimum.