The 5DS-R doesn't have quite the burst rate I'd hope for. It's about 4 or 5 frames a second - half that of the Canon 7D II, and about a third the rate of the new 1DX Mark II. But that's really only important when shooting birds, or perhaps a few other types of fast-moving wildlife. And 4 or 5 rounds a second still generally works well, even for birds. The focus acquisition is stellar, too. If the light is fine, I'll still often use the 7D II for bird photography, but the 5DS-R has supplanted it for nearly everything else, increasingly including birds. Unfortunately, it does not handle high ISO ranges very well, which is a handicap, but again, that generally only comes into play (for me) when shooting birds.
Here's a few 5DS-R examples from the past week.
NOTE: The following images are minimally edited JPEGS. Had I used the RAW files, and spent more tweakage time, which I don't have at the moment, the final product would look even better.
You can see the camera's unease with higher ISO ranges beginning to manifest in the warbler shot. I let the ISO get a bit high - 1000. It's best to try and keep the ISO to 800 or lower, but had I been closer to the warbler and not cropped so heavily, this would not really be a problem. And if the crop were not so extreme, ISO noise would not be nearly so obvious.
If you're in the market for an excellent DSLR camera, I'd highly recommend the Canon 5DS-R.