Thanks Eric and Jakov!
You can't go wrong with a walk like this. I must say though that it was cold in that area (around 6-9 degrees). My wife and I kept telling each other that it would help us prepare for winter time here. ;-)
Regarding your question. I guess the term "best" depends on what you're using the camera for but I think it comes pretty close to the best jack-of-all-trade cameras. I am amazed by the low light performance, the focus speed, the handling. Size/weight is great for travel. The grip is excellent too. There might be better options in each area but there is no camera that performs like the D750 at all levels.
What I don't like about the D750 is the 1/4000s limitation. You hit the max. easily in bright light with fast aperture. ND filter comes at rescue but it takes time to get the ND filter, screw it on the camera, etc.
For bird photography a 300mm + TC is a bit too short so cropping is necessary. The extra pixels of the D810 would be useful in these circumstances. I may add that camera one day for macro and crop-work (crop not crap although the two go well together in my case).
I thought I would not like the mode selector with the scene modes but it turned out that it did not bother me either. All buttons are there. I am ashamed to admit that I haven't been able to figure out yet how the U1 and U2 modes work.
I don't have important issues with the various buttons. Independent AF lock and AE lock would have been handy but alternatives are available.
Peter, how do you like the D750? Isn't it the best camera you have ever used?
I am thinking of buying one and I am curious to hear what you DON'T like about it?
I held it briefly last year during Photokina and I was impressed. Never thought of buying one because of other bodies that I have...
Finally, you should know, I am asking you all this because I like your images 
