What is the point of Thor's ult?

It has enough warning that anyone can just run out of it even without movement abilities, Thor's maneuverability during the floating charge is lackluster, and it doesn't even quite 1-shot squishy heroes, as far as I can tell (maybe I've only hit people with shields?). Of course the game doesn't actually give us damage numbers on anything so I'm not 100% sure about that last one.

Am I just using it wrong? I've tried to combo it out of stuff, but I don't think he has any other CC except the shove from his dash, and people can move out of that fast enough