WHAT THEY SAY...
This is a KILLER Sports Kit
Right off the jump, the Canon RF100-500mm F4.5-7.1 L IS USM is an excellent lens. It is phenomenally sharp, its autofocus is fast and accurate and the build is exactly what you would expect and demand from an L-Series Canon Lens. And in the same breath I would suggest you have vision or goal on how you're going to use this telephoto zoom lens.
Over the past month, I have been using the RF 100-500 paired with a Canon R6 body mainly for sports, although I have been birding with this kit also. The files generated from this combo have been excellent, but there is a learning curve.
If you are going to compare this lens to one of the big white $5k+ primes this lens will never win on file rendering and bokeh alone, that's not why this lens exists. This lens is about providing versatility in a focal range, being physically lighter and, letting you go out with one lens and having the ability to capture 90-95% of what you see.
I love this lens now that my expectations don't exceed the capability of the glass. I know at the long end subject separation is not great, so I try to shoot with a clean background in those scenarios. If you can get closer to your subjects the compression will be beautiful, and everything in the background will just fade away.
We all know in photography there are always trade-offs. Knowing how focal length to subject distance affects a photograph in this case will save the shooter from any perceived flaws they may think this lens has.
I would highly recommend this lens to anyone who wants versatility, portability, and weather-sealing all in one package. If you have any doubts about this lens ask the great people at Paul's Photo, I did and I'm extremely happy with my purchase.