This is a great photo-only review of the R6:
Of note, BIFs work great, especially with a f/4 or better lens.
The biggest new finding is that the frame rate is reduced to 9 fps when the battery charge drops below 60%, and 7 fps at some point below that. This reduction happens with the R5 as well. For someone like me who is a big blaster, this is a bit of a deal breaker. I love my fast frame rates and I will lean hard on the shutter button to get as many shots as possible when there's action. I suppose a battery grip would help lengthen the time you can get the peak 12 fps. But now that I've had the taste of 16 fps from my 1DX3, even 12 fps is a bit pedestrian (spoiled, I am).