Had a chance to play with the D5 and D500 last night at a Nikon rollout at the local camera superstore. I was specifically interested in the D500 to go along with my 200-500 lens (to replace my 7200). My take on the D500:
Crazy fast @ 10fps and big buffer + XQD for speed
better ISO (also crazy for a DX, although I've shot @ 40K on the 7200)
tilty screen like 750 with touch capability
sub selector allows you to move focus points easier
ISO button now on top right eliminating need to map video button to ISO. Gives manual shooters one hand control of exposure triangle.
The D5 is even cooler (of course). They're touting expanded ISO (Hi5) of 3Million. So, I took some shots at Hi5 (with SS high and @f/22) and yeah, there was noise, but there was a photograph. Then shot @100,000 and things looked good.
Since I just got the 7200 to go with my 200-500 in October, I'm going to give it a chance before dumping it for a D500. Plus, being a cheapskate, I like to buy refurbed and it'll take a while until a supply of refurbs hit Nikon's site during a 10% off sale.