When I just bought BF3 I played 5-6 hours multiplayer, then I completed single player(took me about 4 hours), then I came back to multiplayer and co-op missions(different from singleplayer).

Single player was very fun to me, I admit it's kind of short, but it's fun maybe because I speak both languages they use in game and I didn't need subtitles. I loved the mission where you get bombed by a jet almost in the end. I personally like that it's only 4-5 hours, maybe because I get bored when I go through a lot of scripted events and I bought COD black ops a long time ago and still haven't completed single player.

Multiplayer is fun, it so much fun, different game modes, a lot of weapons, a lot of upgrades for weapons, tactics.

Co-Op is fun too, I don't like lack of communication in co-op, but it's cool still.

Make sure your system can handle it, my laptop does it well, but i play it 1366x768.

P.S. FUCK MORTARS !!!