All of the new icons are horrible, they look like google now icons. Why is nothing centered. Why are all the animations supper laggy, they are running at 30 frames and you can see it skipping and it makes me nauseous. Why is nothing centered? Why is the dropdown on the lock screen full screen? Why did it change all the settings and app permissions? So many horrible design choices this is not an apple product. I did not buy an apple product. Please stop trying to give me a *****ty apple product. Why do i have to swipe up on the massive screne to close apps (I now need 2 hands rather than 1). What are the new app icons. Why does my phone feel like a $100 one rather than a $1000 one? Why is the time in horrible blocky font on top of hotbar? The new UI makes me dread using my phone and I do alot of reading on it. Time to get out my kindle. Lost basically everything I liked for dark mode.
Back up your data to the cloud or to your computer using Smart Switch. Then do a factory reset. I've been using Note phones since my first Note 3. After an update you wait a few days for things to settle in. After a few days and you are still having problems, backup, reset and restore and it fixes all the bugs with operating, lags and crashes.
If you don't like the icons, get an icon pack. If you use a theme, get one that is designed for One UI and not Oreo. Try night mode.