At first i was a little bit frustrated because i thought that there would be a lot campers, but it's important to play tactically and to hide and use cover. So it's not simply floating around and shoot at everything that moves and it definitely takes some time to get used to it, but then it's really huge fun.
Regarding the performance.. i guess my system is at the lower end of this forum, but i have no problems. But it's not a console port, so it really uses the hardware
Disabling AO and reducing AA, post processing effects and the resolution should help those with weaker systems a lot.