I installed the iOS 11 beta over the 10.3.3 beta, on a 6+ and was getting horrible lag opening apps, and generally didn't feel right. Was going to pass off as normal for a dev beta 1, but had a nagging feeling it could be better.
I seem to have iMessage in the cloud working, so last night took a iTunes backup and wiped settings and content from the phone. I did not restore a backup, I set up as new.
I am VERY pleased that not only have my messages restored...but my Heath and Activity INCLUDING achievements have all restored too!
So happy, and the phone is running way better than before!