The game was initially set for 30fps, seeing as the graphics are extraordinary. It seems Ubisoft has used every ounce of graphic capability on next-gen technology that they had to cut it down to 30fps. I played it at a friend's place, very fluid, smooth, harder and much challenging combat, new kill animations are great, and the customisation is just superb. The co-op had a little bugs, but Ubi recently released a patch update on the platforms it runs in.
The co-op was really great, I have to say. Playing with a full squad adds more awesomeness to it, except for the fact that your teammates forget about stealth and go charging right in.