Using 8.1 on the 5c and absolutely have no problems, also not with apps crashing wich was totally different with 8.0.2
Battery life seems to be good or even better for me.
Battery life on my 5s running iOS8.1 is better now than when I first updated. I allowed my battery to drain to 0% and then did a full charge to 100% a couple of days ago and my battery life is now better than it was on iOS8.0.2...good to go.
Nope nope nope nope nope. I only used WhatsApp and Instagram for about 10 minutes and read manga for about 10 minutes and battery was down to 80 odd. But weirdly enough, it is the home and lock screen that is draining the most battery?
Battery life for me on my 5C is the same/good as it always has been. After every update I always turn off/on my device and then let the battery drain completely till it dies and plug in undisturbed till its 100%.