The AF is great and significantly better than my previous Canon (1D X), and obviously on a different planet compared to the H5X.
I'm not into video but for the little I do the R5 is vast overkill... Speed is also plenty for me. I wish they gave us the option to select a frame rate between 1 and 20 for the electronic shutter...
I think the R5 hits a sweet spot of price / performance. I like the resolution although if I could have more than 45mp I would take it.
In my mind it is ok till ISO 3200 but beyond that you need the new fancy AI NR solutions. Lucky me I have just bought DXO and Adobe announces that they have added it to ACR / LR as well :/
Generally speaking the sensor delivers although I do prefer the colors and crispiness of the IQ1-80.
About lenses... for me it is a mixed bag. There are gems for sure (I love love love the 2 f/1.2 primes) but they are expensive and heavy. The cheaper options are meh at best. And if you look at good RF glass the line-up is still missing a lot, especially in terms of wide fast primes. On the good side EF lenses work great on the R5.
So with good glass it's a great tool, but prepare to pay for it and to carry it.