Yep, have installed it. Stable yes, not many issues that i've discovered. All apps worked, games worked and streaming videos is also just fine.
at-least on my mini 5, battery has taken a hit but then, i now work from home all the time so charger is always closeby.
the only feature that i have found super useful is quick notes; i do use my mini as notepad for official work and meeting minutes, etc. and quick notes is just the thing i needed when i am connected on the meeting and require something to note it down.
rest all, is just as previous ios; widgets and memoji's are really gimmicks and not very useful to me.
Private relay hasn't worked for me at-least, so will try next beta and see if that works