Haven't checked in here in a while, glad to see all of the activity.
Adapted lenses: flawless in every way. I have had zero issues using all of my lenses. I said it early on in this thread: the 50L is a rockstar on the EOS R. The 135L and 85L f/1.4 are also exemplary, and my 24-70 f/2.8 II basically lives on this camera as my family documentary rig.
The things I love the most about this camera:
1) WYSIWYG has drastically reduced the number of photos I delete in post. No more binned photos from under/over exposure because it's too easy getting it perfect in camera. I have EC tied to the control ring adapter, which is just an awesome feature. It used to be that only the 1-series got metering tied to spot-AF, but that's really not a big deal anymore when a quick twist of the control ring can get your photo just right.
2) The sensor, and how easy it is to work with in post. I'm loving the look I'm getting in photos, with luscious colors and great detail. Noise control is exemplary, for the most part I don't hesitate to shoot at any ISO value. They say it's just a tweaked 5D4 sensor, but as a former 5D4 owner I can say that the results from the R look and feel completely different. Both are great, they're just different, and the one great characteristic they share is how malleable the files are when making big changes in post.
Now, for my negatives:
I use the R for everything besides bird photography. For birding, I'm finding it inadequate because it's AF responsiveness is just too slow, and that performance with extenders is dodgy. The AF seems to start hunting too easily in brushy environments, and initial lock on with small, erratic birds is a challenge. I can see the R being suitable for non-moving, perched birds or shooting from a blind when things are more static, but in run-and-gun situations in low light, woodsy settings where quick reflexes and timing are needed to capture a flitting Warbler or Chickadee, the R just doesn't cut it.
The touch bar: it was a nice try by Canon to introduce an innovative feature, but I'm not a fan. It's too easy to accidentally bump it and change a setting, or when you put that 2-second lock activation on it, it's too slow to make quick changes.
Canon fixed the small point in servo, so that's no longer a thing, but Canon isn't giving us new features, they're patching the camera to bring it up to basic standard.
Overall, it's a fine camera that's rounding into form, and it's super fun to shoot with! The RF lenses look sensational, especially that 70-200. I'm really interested in the 35mm f/1.8 for general use because it's so small, and my wife wants a macro lens for her projects. She actually uses the R more than I do, and recently proclaimed it to be "her camera"