Jax less tanky but more damage. LOT more damage. He's gonna be poopy vs casters now, but hey that wouldn't be a challenge otherwise.
As for his counter strike, that's fine. It's a trade off. Higher CD but guaranteed dodge window. Guaranteed dodge window if it's looking like 1.5/2 seconds is pretty good looking since it also doesn't really tie him up in any way. Gonna have to wait and see what he comes out to be, but that kind of mechanic is easy to be strong if they don't have it on a short duration.