From the sound of it, it seems that most people enjoy the Peacekeeper when they use it. (I'd kind of expect people without the DLC to cry that it's OP- simply because they don't have immediate access to it.)
I'm still looking around seeing if this is worth the asking price though, since I don't particularly want to buy the DLC yet!
I also didn't expect much from any of the new maps except for Hydro, since it added a map hazard.