I'm having a blast so far (no pun intended). I've been focusing on the support/mg path for the moment and loving it. The difference take a bit of getting used to but I love the new setting and mechanics! Vehicles no longer totally dominant (EMP grenades shut down tanks, walkers and screw with vision and there is an unlockable AA weapon for engineers). The vehicles themselves are alot of fun to drive/fly and the new aircraft are easy to control.
A note for any other people using support: the deployable sentry guns suck at range, but are amazing up close. Put one just around a corner or in an alley so anyone entering its field of fire is close enough to get the full burst in the face and watch the kills roll in. A kinetic shield, a sentry gun and a prone mg make for a very effective way to hold a position.
I think I'll be trying Engineer next, I really want to try that Anti-Tank rifle.