Whenever they do that I just wait till next fight, counterpick Mitsurugi, 3A, then combo them. When you get Mits started he's tough to stop.
But, yes, Apprentice is very good. He's basically Spawn ala SC2 but given extra range, speed, and a Force bar. I think that might be the main reason you aren't allowed to do Custom Star Wars characters - we'd all get sick of Apprentice style everything.
EDIT: Actually in response to the OP, I think that SC4's biggest mistake is not including the bonus styles they had in SC3. I loved Wave Sword, Dagger/Bomb, and Greive Edge, if only because I could make a Drizzt, a Thief ala 8bit Theater, and a Chuck Norris
I'm saddened they got removed but God willing they'll balance in the next game.