Hi Guys
It might not be as relevant but here goes...
Im runnning an S5 but have been tinkering with custom roms since my S2. South Africa is always months behind when it comes to updates so I would flash official samsung updates from countries that have already released it.
If you are running 5.0 you are going to find your phone running slower and slower. I loved the UI but as time went on the phone was getting quite frustrating to use. There was an added bug where your battery life would disappear because of a media server app hogging resources when idle. Restarting frequently will solve the problem but it still bothered me.
I did some reading and found a custom ROM called blisspop which is a modification to the popular cyanogen mod and I'm running that. Its been absolute bliss (pun intended), my phone runs like a bullet at I've come to prefer the vanilla android experience as opposed to the samsung version. Don't get me wrong it does have its fair share of surprises, keyboard will randomly close once in awhile because of an error but pop right back after, but none of these problems have been significant enough that I wanted to go back to the battery hogger samsung released. They release updates almost weekly that you can install but all your original settings and apps are kept every time. I did unfortunately have to wipe my phone due to a buggy release two weeks ago that wouldn't let me update but that was more because I was too lazy to find another solution.
There are a ton of guides out there when it comes to flashing your phones and don't let bricking scare you. Almost anything you do is reversible and you can always go back to the stock standard if it doesn't tickle your fancy.
Anyway, that is my two cents, use it or don't use it
-Meh