Thanks to the OP for starting this thread. It's always the first question I have and up until iOS 10 b1, I usually would wait till b3 or b4 (after learning the hard way on a previous version - don't remember which but it was years ago).
Installing on my iPP 9.7 now, since like many, should things be problematic, it won't have major impact on my work and critical / heavily depended upon apps & features. If the bugs are tolerable like iOS 10 b1, then I'll give it a go on my iPhone 7+ and also install watchOS 4 which I assume requires iOS 11 be installed on the iPhone to which the watch is connected.
I'll advise as to the results of all 3 of the above devices assuming things are good enough on the 9.7. Thanks to all for sharing their experiences so far.
UPDATE: Been over 24 hours and iOS 11 b1 is running well on my iPhone 7+ and iPP 9.7. Surprisingly, so is WatchOS 4 b1 on my 1st Gen Watch (42mm Stainless) and seems to be less buggy than iOS, but there's a lot less going on in the watch software (or so it seems).
I'm definitely not upgrading to High Sierra till b2 or b3 as I don't have a mac newer than mid-2012, but since this is a thread about iOS I thought I'd throw in the watch and MacOS comments for people like me who are thinking of upgrading /have upgraded across the platforms.