As someone who's been a Stock Android fanboy and got his first Samsung in over a decade, the only significant change for me is:
Keep pop-up windows open – Instead of minimizing pop-up windows when you go to the Recents screen, pop-ups will now remain open after you leave the Recents screen so you can continue what you were working on.
Password managers work perfectly well in popups. Calendars, stickies/notes, and other scensrios where the app isnt your focus but you need the utility of that app within another app.
In addition to what the other person wrote - popup windows are very useful on large screen devices like foldables and tablets. I'm on Fold 4 and the popup windows have been great for multitasking, like keeping an eye on a chat (or how far away your Uber Eats is) whilst you're doing something else in full-screen. Using a Fold is more akin to using a desktop, so multitasking features like this is much appreciated by folks like me.
If you want a good product why would you get something from Samsung? Garbage company and garbage products. My s10 died shortly after the warranty expired and their tv's are riddled with ads, on top of that their warranty service is practically non existent in Canada. Fuck Samsung.
I have been through about 3 Samsung phones now back to back, which has been about the last 8 years and they are great so idk why they are getting so much hate. I had either the 1st or 2nd pixel phone prior to going Samsung and I thought it was awful. I found that I did enjoy some of the extra stuff the UI overlay builds in. For example, at least back then and may not reflect today, pixel didn't even have a way to display battery % by default. I think you could through turning on developer options but it was not as nice. Does the Samsung UI come with a lot of stuff I don't use? Sure but I also don't think it impacts it negatively anyway so who cares.
Also I hate iPhone and think it is the worst UI of them all. I use it daily for my work phone and really have no idea how everyone believes its the best option there is.
Pulling down from top right corner to show the full quick actions menu. Now I need to swipe down twice to see all options, with this update only once. I will actually install the beta solely for this feature.
To take real estate from notifications (is it somehow a benefit to Google to add scroll interactions?). I'm not sure what the endgame is but the only other thing it achieves is making them always trigger when you're holding the phone to your ear, which no matter how tinfoil I get I can't see any potential motivator for that. It's pure bad design, for the life of me I can't work it out.
There's always the under-the-hood changes from Android upstream, and Samsung keeps adding customization options every update. Without rooting or 3rd party apps*, no other OEM comes close to OneUI's customizability. For me, that's a huge plus.
*I meant specifically 3rd party apps, because Samsung has the Good Lock suite of apps, which needs to be installed from the store. They work somewhat as a beta testing of features or advanced controls for existing features, and many of the features are added to new updates, for instance, the quick settings easy access up to One UI 5.1 (Android 13) is only available via Good Lock's Quick Star module, but seems to be built-in on One UI 6 (Android 14)