I've been using my R for 4 days now and I have to say I'm impressed.
Good things are that the autofocus performance both with the R 24-105 and with adapted lenses (16-35 f/4 and 70-200 f/2.8 IS II) is superb.
The body is smaller than I was expecting, only fractionally larger than the A7RII, but grip is good. I can shoot single handedly with the 70-200 attached, which is harder on the A7RII.
The viewfinder is superb. I've been using it at night and today on the beach in full sunshine. It performed perfectly both times, you forget you're using an EVF.
I've got two batteries, but so far I haven't needed to change the battery during the day. Your usage may be higher than mine of course.
The EF-RF adaptor is weather sealed, which is great.
The best thing though is the write speed to card. I am using a 64GB Sandisk UHS-II card rated at 300mb/s and the buffer clear time is absolutely astonishing. I don't ever want go back to expensive CF or CFast cards when UHS-II is now much cheaper (and of course you can use slower SD cards if necessary and they're ridiculously cheap.
If you have an R and haven't got a UHS-II card yet, I suggest you invest, you won't be disappointed.
The control arrangement is fine. I am happy with the new mode switch arrangement, and it makes sense when switching between video and still modes. I haven't used the swipe bar thing yet, but I'm sure I will given time.
Negatives:
My biggest gripe is a tiny but irritating one. The rear caps for the RF lenses can only be fitted on at one orientation, so you have to align the mark on the cap with the red dot on the lens. This is very frustrating if you're trying to change lenses quickly.
It doesn't seem that the face/eye detection is as reliable yet as on the Sony. I need to wait until I can get all the raw files into Lightroom and see how well it actually did, but there were many times I thought it should have locked on and it didn't appear to.
Other than that, I can't really fault the camera. It does everything well.
I'd like one with two slots, with higher resolution, with IBIS and no AA filter. But that will come, I'm sure. In the meantime, this is going to take over as my primary camera.