Multiplayer is where RB6 will give you value, but the single player campaign on 'realistic' was a great challenge, too.
The variety of game modes in multiplayer ensures a rich experience, whether you prefer playing against other gamers or against agressive and tactiacally adaptive artificial intelligence.
As a lifelong gamer (25+ years), I can say this is a very rewarding experience.
If playered with 5.1 or 7.1 surround, get ready for automatic gunfire to ring your ears and drive your room mates/spouse/fill in blank to buy some bose headphones for you.