Been playing it for awhile now. It's a blast, especially when you get friends together. In my case, my cousin teams up with me. Since the guy has been a marksmen since killzone 1, lets just say no one gets past him easily, lol.
Some things I've noticed.
1. Everyone either runs around as a medic for the drone yet do not heal, a engineer that never builds turrets/fix stuff, or my favorite, whole entire teams of infiltrators.
2. The unlock system sucks, in the means that I miss having a regular class with our favorite Helghan assault rifle of doom.
3. The infiltrator be cursed, hated, and hunted till the game release. It's already been talked about getting the nerf stick.
4. Being a expert tactician = my version of said nerf stick, lol.
5. Watching my cousin take top rank constantly for several matches = priceless.