I placed an order for the Nikon D850 camera on the morning it was announced (August 24, 2017). I'm anxious to get the D850 for the following reasons:

1. I'm currently shooting with just one camera. I really need a backup, but don't want to buy a backup since I would like my existing D800 to take that role. I feel like I've been rolling the dice too much lately taking photography trips with just the one camera. Going to Iceland this winter without a backup is not going to be an option!
2. I don't expect the images to look a whole different between the D800 and D850. But, I think it will be a bit easier to capture some of the images with the D850. I sold my D700 a while back...and really miss the higher frame rate for sports. The D850 will enable me to shoot youth sports with more keepers again.
3. I'm hoping the D850 will have a quieter shutter as I shoot inside churches a lot.
4. A more flexible LCD screen will help me when I'm laying on the floor under my tripod trying to line up shots of ceilings!
5. I find it challenging to zoom in to focus manually with Live View with my D800. It's my understanding that the resolution is much better on the new screen...and that will make life a little easier.
6. I often shoot wide to create straight lines (requiring cropping) in architectural images. The extra megapixels will provide extra cropping capability.
7. I will enjoy ISO 64 as a base...I shoot a lot of longer exposures.
8. I find the focus stacking feature of the D850 to be intriguing.

Those are the main reasons...but there is no bigger reason than needing the backup!

For those of you who track such things, I placed my order at 8:00am Central Time on August 24th through B&H Photo. I have no idea where I stand on the waiting list...just hoping to get my camera by the holidays!