As you probably already know, this is a buddy cop movie, which is a bit ironic, since McCarthy's earlier secondary role was an identity thief, and it was a buddy-fugitive movie. There are three kinds of cops in this world: an organized by-the numbers that trusts herself a bit too much, a cop that would rather get shot trying to tackle a fugitive down than be seen keeping her hands up as ordered, and a nice little helper. If only there was one of the third.
There aren't many interesting characters, and in this case, it's a good thing. In a cop movie, it's smart to not put too much detail into the bad guys the cops are trying to arrest, if it's the cops we're supposed to be rooting for, otherwise we'll hope they lose. Fortunately, most of the movie is just a silly argument between the two, like when Bullock is forced to make her look like a stripper or someone, by doing some work with her lawyer clothes. Good call, McCarthy. However, every time they swear to someone other than one another, and go out and fight, it's like the disco ball of the bar is flicked off whilst a main character is murdered, and we're not sure what we think about it. Remember all those movies that assault people for being black or Chinese or something? That's exactly what happens to someone who's skin is Casper-the-Ghost white. Cops like these don't follow the golden rule and act as if they will get fired if they don't get the job done, whether it means to tackle down a little kid or to get drunk at the pub while on duty.
The Heat is like a police siren right in front of your face. You're not sure what it's for, and pretty sure if it's for you, it's not good, it's way too loud, and gets predictable when the honking rhythm goes on and on.