Well, I just had a brief moment yesterday night to have a glance on my new D850. My first impressions:
It is a Nikon... For the moment no, RTFM for me though there are obviously functions that I know absolutely nothing about. After having used Nikon since the late 80's, I can pick up the body, set the basic stuff to the way I like and start using it. I do intend to get to know the way the AF works intimately.
The first thing I did was to install the DK17 on the body. Indeed the finder is really nice! No, it is not in the realm of the H5D60 or 40 but a real upgrade. For the first time in the digital era I feel like it is like the F5 used to be!
I can only compare to the D800e I have but the body seems higher, or at least the grip seems to be and also a bit deeper making it easier to hold.
The screen is WAY better than the one on the D800e. For the first time I like the image I see on the screen.
No more pesky pop-up flash!!
Oh, did I mention it handles like a Nikon?
I have not made a lot of images yet (only a few actually) and the ones I made were only in my near vicinity but just to be fair I have pasted some below with a couple of 100% crops. Made at ISO6400 (on the D800e I would never go beyond 3200 but I feel this is tolerable maybe a stop more). Images are Jpeg SOOC.