Having installed High Sierra on my MacBook Pro and finding it very good, I decided to do the same on my iPhone 6s Plus and wished I hadn't. I had problem after problem with main Apple apps missing and terrible Internet connection. I tried everything possible, including switching off VPN, but it was all falling to pieces and impossible to go back because, because of the sad state of affairs, I couldn't even get to my backup. So I decided to make a last try and deleted Opera VPN and bingo. OK, it took me two hours to re-organise all my icons but everything is so much smoother and faster compared to Sierra. It's a real joy to use and even my most important third party apps only have the tiniest of glitches in them.
So, I can highly recommend High Sierra Beta 2 but just watch that you're not caught out as I was.
So, I can highly recommend High Sierra Beta 2 but just watch that you're not caught out as I was.