I hear that the UI is a pain with a keyboard and mouse. Should I probably play with my controller instead?

yeah, go for it

it's not like this is a FPS where pinpoint accuracy is needed

BUT it's annoying as hell knowing you'd hit your target if it was real, but you couldn't because of that stupid controller.
I'd go mouse+keyboard.

Playing ps3 myself, so. Controller. But still. If I had it for pc, definetly mouse+keyboard.

I would personally suggest trying it with both before making a decision, everyone has different opinion's, and to some people the UI could be easier to use the M+KB then the controller. I am getting the 360 version so I have no choice in the matter lol but yeah I suggest trying both setups out yourself just in case.