The "bugs" I was able to find so far which will make me revert to 11 for the moment. I am using a 9 Pro LE2123.
1. AOD is not AOD anymore - activated the AOD, locked the phone, AOD stood on for few seconds then black screen.
2. No search function - I am not using drawer for the apps and for me was drag from the bottom - upwards for the search function. The only way to search for an app is through shelf - extra steps, slow process
3. Unable to get rid of google news page (left swipe) - Tried to go on home settings by pressing an unused spot on the screen. Not having the option of removing it.
4. Bubbles - icon way too small, when opened is not wide enough to fill the screen so you will struggle to write.
5. Font - Too small - it`s either too big or too small.
6. 1+ weather and clock...different font, no longer red 1.
7. Shelf - bit slow when you`re opening.
8. Clone apps - Now they made sure you know it`s clone app as after the title you have word Clone in brackets.
9. Drag to close the bubble...you need to go straight to X spot in order to close as it won`t close only by dragging down towards that X (as it was on 11)
10. No more signal in London Tube. While yesterday before update I had 4G signal, today I have none.
I might add during the day as I get through it.