I got in the beta for this and it really kicks ass. It's got "classes" like many shooters these days but you can create your own classes as well. The classes are pretty much just the kind of gun you spawn with, so you can be a sniper, heavy machine gunner, assault rifle user, etc.
No "engineers" or stuff like that.
The game has "levels", which you gain quicker by doing well in matches. The more levels you get, the more stuff you unlock. There are also "challenges", such as getting 75 head shots with a sniper rifle, that unlock other things as well, like gun attachments or camouflage patterns for the gun. There are also "perks" that you earn that do things like making your bullets do more damage, or make it so after you lose all your health you lay down on the ground and get one last chance to kill someone with your pistol.
My favorite custom class right now is an M4 with scope, a smoke and frag grenade, perks that allow me to do more damage and penatrate walls easier, and an RPG. You could even carry a sniper rifle and an RPG if you wanted. You only get one of each grenade unless you have certain perks, so grenades aren't spammed too bad in the beta. Also, you can always pick up any gun you want since guns drop when you die. You can even pick up a gun that's better than yours (because the carrier was higher level, for instance).
Another thing that's cool is that you get rewarded for getting multiple kills without dying. At 3 you get radar, at 5 you get to do an airstrike anywhere on the map, and at 7 you get a helicopter that automatically flies around shooting enemies.
It's great. It's like old school and new school mixed together for the perfect balance.