I have used the Nikon D750 for little over a year. The picture quality is great. Ergonomics are good. The aesthetics of the camera makes you feel that it has been made to last long.
Low light performance is also great.
A lot though remains expected of the video mode, no 4k recording and the AF in video mode leaves a lot to be desired of. Video in my opinion is a strict no no since it hunts for focus a lot.
A lot of people are not happy with the 1/4000 ss but in real life although it does not hurt to have a 1/8000, does not feel a necessity.