Have even played in level 55 bracket?Crit rating has been nerfed which means that maul will crit very rarely. Even if they do they still don't hit like some sniper abilites. Everyone has a lot hp, armor rating and a lot of survivebility in general. So assassins/shadows can't burst or stunlock to death anyone. And once their burst is gone they are like sitting ducks beacuse of no sustained. Add a healer to opposition and they can't almost anyone. So no, class is not a god mode. . All you have to do is slow them, root them and make sure they get behind as few times as possible.
However in pre 55 wz they do seem to take out ppl extremely fast. But so do snipers, marauders etc. so thats more of a bolster issue.