I have had Lollipop on my S5 now for a couple months (Verizon) and it has been a complete science fair project. It should have never been released. The battery drains much more quickly, the screen blacks out when I am on phone and won't come back on, the phone locks after Bluetooth calls, the keypad on the dialer is smaller and doesn't take advantage of the large screen, etc. etc.
In a word, it stinks. I can't think of a single thing it does better that the previous OS and a lot of things are worse, especially the battery life.
And yes, I have done a factory reset twice and had to re-install all my apps and re-organize my phone and it didn't improve anything.
Lollipop was pushed-out to me by Verizon and I did not have seem to have a choice in whether or not to accept the update. This thing needs major improvements before it matches the stability of its predecessor.