So I'm not sure if I'm the best person to be giving their opinions as I've used only OP phones for the last 3 years, so the things I like might be standard android these days. Also, rereading my comment I sound like an OP fangirl, so feel free to disregard my comments.

I love their aesthetic. I like the "bubbly" feel to the UI, the font, color choices, etc. I think they're very snazzy. I also love the customization features, specifically the launcher editing UI (it's stupid intuitive), the AOD options, they have their own creepy animoji thing that I kind of love, the transition animations are smooth, and it's cohesion in general is excellent.

It all feels like it belongs together. I have a hard time determining where "standard android" and OxygenOS begin/end. It just feels nice to use and I love leaving my phone faceup just to look at it. It's hard to identify exactly what I love because I haven't been keeping a list or anything, but just this morning I was moving some apps around and between folders and it just did exactly what I wanted in a way my old phones definitely wouldn't. Small, but really exciting in the moment.

Of course, these are all very little things that might not be enough for other folks, but the little things are usually what delight me most. I'm also not a bank, so this phone is absolutely the most expensive thing I own and I try to appreciate it when I can.

I will say, there are things that OP will need to change. For me, things like icon customization and notification dismissal direction need updated. But these are extremely low on my list, so I don't mind it as it is.

I want to add that the hardware on this device alone is worth it to me. It's a beast and the battery is fabulous.

Anyway, I'll stop gushing haha. I didn't realize how much I like it until now. I know these devices aren't for everyone so this is my own opinion. I'm also writing this on my commute so I feel like it isn't coming across as clearly as I'd like. I hope that helped a bit though.