Battlefield is a great game, and here's why.
Enough of that though, Battlefield is all over the multiplayer, just announcing a couple of days ago at E3 that they are introducing "Premium" the DLC that comes with 5 DLCs as well as other in-game content. This alone should tell you that DICE, EA, and Frostbite are committed to their game.
Coming from Call of Duty, at first you notice that the maps are giant, and it may take you close to 5 minutes to run across, something that I thought would be a problem. However Battlefield thought of this two and carefully concentrates the action around M-COMs (bombs in MW3) and other objectives. This allows your squad and teammates to set up strategies that will help yourselves. If you feel you aren't committing enough murder, BF3 came prepared with a few versions of death-match including ye old TDM.
All in all BF3 has a great multiplayer that just nails the teamwork to the ground and should definitely be tried out.