I can't believe some people are arguing that they don't want/need to be able to lift shadows from a 5 stop underexposed shot. The fact that you can do it is ABSOLUTELY AMAZING. If it were a Canon sensor people on here would be singing it's praises and bowing at it's very existence. Since it's a Nikon, well meh...
True, you should never shoot a shot 5 stops underexposed. But you can see even with that shot there is no banding (or very little). That is the amazing part.
It is better to have that capability and never use it than than not having it when you need it. Kind of like a 600 HP car. Yeah, never really going to utilize all that HP on the road, but nice to have just in case...
And it's not like Nikon sacrificed anything else to achieve those results. The 1/4000 ss limit was an artifical limit not to cannibalize D810 sales. AF is even better now, high ISO still continues to improve. I am impressed by the D750. At 24mp it is the right amount also.