I had heard the base iso is not so good. DP review, angry photographer, and others.
The point is that my D7000 does better in Dynamic Range then the D5 at ISO 100.
Why this is making such waves is that most people have been saying Canon is no go due to the limited Dynamic Range, which is better in Nikon and Sony.
The fact that Nikon had to put up compromises, probably reading speed of the sensor to get to 14fps vs detail of the reading (dynamic range) is just a reality check, the D5 is still as good as a Canon.
When you take pictures at the right ISO this is no issue at all, you have sufficient dynamic range.
When you take a bad picture at ISO 100, you will have less possibility to recuperate it on the D5.
When you take a sports picture at ISO 12500, you will see why a D5 will sell (as will the Canon 1DX MKII).
I think Nikon may have dropped the ball on this camera. I haven't used one obviously, but the demo's and test's that I have seen show it to be worse than other far cheaper camera's. Granted, the soul of the D5 is for use in sports and other fast paced environments where 3d tracking and 200 burst @ 12fps are a basic requirement.... but for general photography, even wedding photography which I use 2 D4's, I am struggling to want to upgrade.
The D750 on the other hand, looks amazeballs.
I was looking at wildlife photographers: AF as good a 4DS, feels more reassuring. Less missed shots in action. Whitebalance is spot on. Higher detail due to increased pixels. => it does what it is made for
D750 - D810 might be better suited for weddings, but that is not my subject, so difficult to have an opinion. Some pro shootings have been done, I did not hear that photographer complain.