So basically, the moment I installed OneUI 4.0 I noticed it wasn't anything special.
Then a day later I noticed background (standby) battery usage has gone up and I can't last through a day with it.
If you use swipe gestures to navigate, if you swipe up slightly and let go you will see the edges of the app are not filled (as the animation is transitioning from a recent apps "card" to an app) you can also not use the app for a few seconds until that transition is done.
Previously working, now broken codec/VideoTrimmer app which makes every render useless, videos will either have no audio or won't upload at all. The workaround is to render the same video again as a "Movie" when you go to "Create" in Gallery.
Why do I have to suffer for an incremental update, OneUI 3.5 did just fine. I will most likely rollback to it, since even if we get update 4.1, I am sure it won't fix any of the aforementioned issues.
True, I am an S10+ user and I love the phone, however the OneUI 4.0 ruined a few things I used so often. Especially the VideoTrimmer app... I used it almost daily. As per UI issues, it's even worse as you use your phone's UI every single day, and for OneUI 4.0 the UI took a few hits, at least for the S10+ variant. Other phones might not have the same issue. I don't even know if we will receive OneUI 4.1 - I hope we (S10/Note10) get that update and it fixes the issues.