I've updated my 2 devices (a P8a and a Pixel Tablet). Thanks to the GOS devs for their hard work!!
As others have pointed out, I've found the new UI design to be less appealing than the previous one. I hope Google changes it for the new release.
I've also noticed some changes regarding gesture navigation. I would say the sensitivity has changed, and the animations now feel a bit slower. I much prefer this new version, less prone to errors when triggering the UI gestures.
On my P8a I think I've noticed what could be a bug. Before the system update I had airplane enabled, but afterwards I think it was disabled. Usually I'm very careful handling the UI, so I tend to think this was due to some bug and not an action on my part. Would like to retry the update, to see if it's effectively a bug, but cannot do it cause I don't have another device to test (my only option would be to unlock the bootloader in order to reinstall the previous version, losing all the data and having to setup everything from scratch). Perhaps someone who hasn't updated yet could test if there is effectively a bug regarding airplane mode.
(This was my exact configuration before the system update: airplane enabled, WiFi enabled, Bluetooth disabled).