Looks like a French computing magazine got hold of an ES,which is running at around 3.15GHZ(according to what is said on Reddit):
https://i.redd.it/tic6i57uob5y.jpg
So in gaming it is 10% slower than a Core i7 6900K and 8% in non-gaming software.
If they can get clockspeeds up and Turbo running properly,it might actually be not bad!!