I am leveling by pvping currently 38lvl, I have to say that there is balance at the moment between all classes, I havent found my self killing more than dying on 1v1 when I fight ppl at the same level with me. Every spec has its weaknesses and strengths.
If you stand still and let an assasin get to you stealthed its your problem I have like 4 abilities to reveal stealthers.