I'm not very far into the game and didn't really touch the beta, so my voice isn't one of experience. However, from my seven or so hours of playing, two-handed weapons seem to be a perfectly viable playstyle. Damage is good and man-at-arms abilities are versatile. There doesn't seem to be a legitimate trade off for taking a shield, though, at least not early game. Damage is lower, and it doesn't mitigate damage reliably. Fighter cooldowns could be lowered across the board; there's no reason some of them should be effectively one-battle only.