i bought arma 2 in the sale recently, and it's not a cod style shooter at all. it's much less arcade-y and aims at realism, a bit like a serious grown-up version of bf2, with a steep learning curve. you've got to put in a few hours of hard work going through the tutorials before you get to the fun.
no major bugs nor issues experienced so far, except for i still can't get my head around flying the choppers! but then again it did take me a good while to get the hang of them in bf2. oh, and patchy voice acting too!