I have only recently taken ownership of this body and it certainly is a step up from my 6D. It has a 30.4-megapixel full-frame sensor, Dual Pixel CMOS AF, with an amazing 61-point AF system.
The 5D4 can record 4K video at up to 30 fps. However, Canon decided to go with the motion JPG codec which has a very high data rate and uses up a 32 gig card with only 8 minutes of video footage. The captured material is stunning though.
Below are a few images I have captured with this camera.