I had a chance to play the Xbox One X at EGX yesterday and it was extremely disappointing.
In the case of Assassins creed the MS Rep said beforehand that it boasted amazing 4K graphics, ultra smooth graphics that was not even using the full power of the system and an incredible amount of detail (advising to use the bird to show that off).
In reality it was pathetic, tearing, slowdown, popup and textures (poor textures) that filled in when you were almost on top of the object. We asked another rep from their tech dept about the poor performance and the fact that it was so poor in general and he basically agreed and said there was nothing they could do about it as they have to work with what they have.
So it's very well for MS to say the the Xbox One X can do this and that but when they are unable to demo anything that proves it then what is the point. Forza actually ran OK but was nothing amazing, certainly no better and probably a little less detailed than GT Sport on the PS4 Pro.
So basically very disappointing from MS who had nothing to show really.