1. battery life time lasts around 4-5 hours in normal condition (mostly including surfing internet and watching VIDs on youtube) after 5.01 updating. -- not satisfied. 2. Screen a bit flickers on low brightness level but not so severe-- acceptable. 3. pretty smooth on L. 5.01. Actually I didn't stay on KK 4.4.2 and upgraded to 5.0 immediately when I got S8-50-- feel comfortable.
for item 2, I had the same experience in my laptop Yoga 2 pro core i7. However there is a graphic driver setting about power saving under battery mode and then I can switch it off to resolve it.