I got to play with one at the Nikon launch party my local dealer sponsored. It's pretty amazing, both in speed and ISO performance. The buffer has to be seen to be believed. Twenty full seconds of 10fps is really impressive. It sold me.
I'd already planned to upgrade from my D5200, it just doesn't have an adequate ISO performance for my needs (wildlife and bird photography). ...and I want to stay with DX if I can.
In the hands on, I didn't have much opportunity to use all the new focus points, but it promises to be another improvement over the D5200. They also had Nikon's other camera bodies on the table, for hands on comparisons. For the price, the buffer on the D750 feels worse than my D5200, and the D610 seems like a step backwards in technology.
Regardless of which way I go, it's a very expensive upgrade, so I just figured I might as well go with the newest DX model. I want the buffer, the ISO and even the Snapbridge is pretty cool. I'm hoping that Nikon's performance with recalls will improve, but regardless, ...I have to admit, that in the long run, I really, really want this camera. Because this is a hobby, and it's not all about logic....
Emotions count too.