The singleplayer campaign is pretty much like CoD, except with more vehicles and it looks absolutely stunning. I haven't even finished t though, I'm not fan of that kind of "action".
The COOP missions on the other hand are awesome. Find a friend to play them with, it's well worth it. And you'll ge nice weapons as rewards.
The main point of BF3, like any other BF game, is the multiplayer. I quite like it, and I have played it way more than BF2. :/
No splitscreen for any version. And if you have a PC that can run BF3 even at low settings, there's absolutely no reason to even consider a console version.