Unfortunately, the 5D4 does not address the major issues I face with my 5D3. Or maybe that is fortunately, as my wallet won't take a hit.
Really needed spot metering tied to the selected af-point.
A tilt/swivel screen.
Full continuous drive speed no matter what the battery level (the 6fps on my 5D3 drops to 3fps once the battery drops below 50%).
I don't have many issues with the 5D3. But those few I have weren't addressed 
I do like the bump in MP, wifi/gps, & touchscreen.
I assume the issue with slow writing to the cards when using the SD slot is fixed.
Anyone know if the 5D4 has a built in radio flash trigger? Probably not, but could have been nice.
Another nice to have would be more DR. But, we won't know that until later.