Overall, since updating to the 3rd beta version, I personally have seen much better performance, battery life, and less bugs compared to the first two updates. I like the tweaks they've made with the UI as far as the color theming goes, but like a lot of people participating I find myself a bit disappointed that it wasn't a more major UI overhaul compared to stock Android 12. I do like the improvements made overall and I still love my S21 Ultra so I think this has been a positive experience for me and I can only hope Samsung decides to embrace Google's design structure more before the final beta release.
I agree, beta 1 and 2 were good with only slight glitches, and 3 has been rock solid so far and fast. I don't have much of an opinion on the stock Android side. Samsung has continued to win me over with the additional features they add in such a those provided by Good Lock, so I've only had Samsung phones for the past decade. Just my opinion, I know others have their reasons for how they decide.