I have a GS5 on Sprint and after updating to Lollipop a few days ago, this sums it up for me.
Alright, so that's probably a bit dramatic, but I still regret switching to 5.0. I had my phone setup just the way I wanted it. I was perfectly content. When I downloaded 5.0, I noticed several changes (albeit fairly minor).
- UI/animations feel a bit laggy. I went into dev mode and turned off animations. That seems to have helped a decent amount.
- I like to keep my phone on silent when I'm sleeping. My alarm clock (stock) no longer makes any sound when in silent mode. Luckily, I still managed to wake up for work on time.
- Couple of gripes with how the new UI and notifications work with certain apps like Spotify and Poweramp.
I'm sure most, if not all of these issues, can be alleviated with some tinkering, I just prefer to set everything up once and be done with it.
/rant