Echoing other users' sentiments here...
My 6s is running great on 11.3 b1. The phone is much snappier and feels like new. Battery life is better than before. I am a medium duty user, mostly conference calls and Skype for Business meetings, plus the occasional Sudoku game. On 11.2.5 b7, I would end the day somewhere between 25-30%. Over the past few days, that number is now 30-35%. Not scientific, I know. But it seems better for me nonetheless.
I do have a question about iCloud Messages, though. It's turned on (confirmed in settings), but I don't see the messages on my tbMBP running 10.13.2 (High Sierra). Are my messages supposed to show up on the Mac as well, or is that coming in a future macOS release?