Punk99, if you are talking S8+, I don't know where to begin. My S8+ was 2 years old when I read about Pie, kinda casually I must admit, and fell for the hype. I have regretted updating my phone from minute one.
This phone at 2 years old was going great, and I was thinking, hoping, and likely gonna make it another year without upgrading. It was dialed in, battery lasted 90-100% of my workday, and my phone knew me, knew me well.
Things I noticed right away (and I'm not a phone geek or freak, so I'll not be using correct terms when describing some things): the icons on my homescreen (phone, messages, and the other ones that are standard Android/Samsung look, became.... unrecognizable, cartoonish, fuzzy, iphonish crap. I seriously still have to take extra moments when looking for Messages when choosing how to share something, many weeks later.
2. Battery tanks regularly at around just after lunch. I am admittedly a heavy user, requiring my screen be bright, on and off of wifi, but mostly for CRM, email, and reading from the web. A dozen or so pics every day. But just a lot of hours daily. It lost about 40%, usually needing charging with a couple hours left in my work day.
My phone doesn't know me anymore and it's taking it's sweet time, and might not be at all with some apps, learning how to be predictive, or even recognizing the two people I send texts to the most.
I'm failing to describe properly what my phone used to do and what it does our doesn't do now because using it now is as exhausting to me as it is to the battery. But I sometimes just want to throw it on the ground, and all because of Pie.
Others on this forum will concur. Hope it's not too late for you.
Oh! One last thing I can describe better: tap the screen rapidly three times, in most any app, and the display will zoom way in. It's especially STUPID for this to happen when using calculator.