For what it’s worth... (not much)
I now download Public BETAs as a matter of course. I don't see many issue with it. I've never had a bricked iPhone. On occasion I may have an app that doesn't work right and then I remember its likely due to the BETA. Battery is sometimes an issue, but I just carry a spare USB block if I know I’m going to be out all day. Sometimes the OS can be a tad clunky and jumpy but all in all, if you’re on these forums then I’d say you’re geeky enough to:
1) be able to download the BETA in the first place:
2) be interested enough to get a peek at new features:
3) in a worst case can jump back to iOS 11.
Not sure why I posted. But hey BETAs are there to play with new features, so download and play. Just don’t complain if they don’t work – that’s the point!