Already upgraded my 6s and mini 4. I also upgraded both on day one for every release of iOS 11 and never understood the “iOS 11 is the worst” meme, though obviously some had issues with it, like any release.
I like iOS 12, very fast on both of my devices, the mini 4 especially. Nice improvements here and there.
I have had trouble selecting text with the text selection handles, though. It seems to be impossible to grab the selector at the end of the highlighted text block, or maybe I haven’t caught on to the new way to grab it.
Use 3D Touch for selecting text, it'll change your life.