So I have had the update for at least a day. I'm still getting used to it, but here are some of my main criticisms.
Moving the notification clock is a bad idea and should have the option to fix it.
Space wasting in apps. Apps like the stock messaging app now has a gap at the at the top that says... Messages...
Stock email and messaging apps are not working with themes anymore.
Dark Mode does not work with themes, which makes it pretty useless
Settings are a bit too dumbed down for my tastes
Well, I've had mine about 2 days now and I like it.
Moving the clock from one side to the other for me is not a big issue. It's still there, just moved.
Open space at the top of the messages app and settings... No biggie for me.
Stock email and messaging app not working with themes? Not an issue for me. I don't use someone else's theme. Everyone that I've seen in the store looks like bird droppings to me. I prefer to use my own wallpaper and my own arraignments.
Dark mode is totally NOT useless since I don't use prepackaged themes. Finally I got everything in dark mode without adopting someone else's "custom" theme.
My only gripe so far is that they haven't fixed the disaster of removing the option of custom text message tones. A feature that existed prior to Oreo. Please, don't refer me to the fix listed online or using other apps since none of those work with group messages and require you to never delete old messages.