I was hesitant about the update at first, solely because KK had been running insanely smooth for me and I don't generally like to immediately jump into new technology without a decent history of feedback about it (I still cringe when I think about how I ended up with the first version of Windows 8 after the unfortunate death of my XP laptop...8 was a disaster, I downgraded back to 7). However, my phone would notify me every time I looked at it that there was a new update available, so having heard mostly positive things about Lollipop I took the plunge. Have been very happy. Seems all of my settings from my previous version carried over. It has only been 2 days, but so far so good.
Also, am I the only one who doesn't have the google toolbar/searchbar that everyone is talking about (I've read a lot about a search bar that used to be transparent and is now some solid white toolbar that is on the homescreen)? I seem to remember disabling it when I first got my phone. Haven't had it since.
So far the only problem I've had with the update is with the stock messaging app taking a lot longer to send MMS (still sends, just isn't as fast as it used to be). I also got a text from a friend at 2 in the morning that was random and when I looked in to it, it had been sent the previous day, though I'm not convinced that's not a network error...as I've been texting others with no problems and no delays.
The new features work fine for me. I haven't had any issues with the chop-chop flashlight, I haven't had any excess battery drain (in fact I only lost 5% after the update), and the camera seems to be improved. Overall, I'm extremely happy with the update.