I've been using it from day 1 since it was known as Firefox Preview (way before it landed in nightly) and I have very little to complain about.

uBO, Privacy Badger, and DecentralEyes are all the extensions I need. Stuff renders quicker, I can swipe between tabs, reader mode is there. Sure, it might take one additional tap to open a new tab, but I'm fine with that.

I'm now using nightly, so I experience an occasional bug here and there, but I don't care.