I just got me a pair of these bad boys:
Long story short: they are incredible. Playing in the game you can hear so much detail that just wasn't there before. Like hearing an enemy soldier cutting through a gate, and knowing without having to look that they are to your left rear. Or hearing a helicopter circle around you and knowing not to poke your head up above the boxes because it's directly to your front right.
You can hear the firefights in the game and tell where they are in relation to you (and even about how far away they might be), people walking up the stairs behind you, the sniper rifle being fired across the street to your left... it's really intense.
The price tag is pretty steep, but for anyone who has the free cash: get these. They just make the game more fun.
Oh, also: you can connect to two devices with it, so you get your PS3 chat and your Mumble chat effortlessly.