As I mentioned in a different post, I am impressed with shooting in 12K and 8K with the URSA 12K camera.
But the high frame rates in 4K are pretty impressive, too (even with the crop). Here's some 240 fps test video I recently shot...
NOTE: I had one of those hollywood black magic filters on it. I think next time, I'll shoot without it to make things even sharper -- although I like the subtle glow.