If this will be a 10th class to choose from, Valve has proven to be very creative once again. For me.. Where is TEAM fortress going to these days: Hats, dogs, updates, sandman.
Imo Valve do nothing to improve teamplay, which is (the same as for HL2 CTF) for me the reason to be playing a team based game. Just the default weapons, no fancy little tricks to help the solo player, just people's intelligence to win a game.
Maybe I should start play CSS