Aright, so ive left the brightness on max, since i like to view this beautiful screen at its best, and with watching hd videos on youtube for half hour on 4g service, and using the phone all day surfing web texting, and on line with customer service for about 40 minutes, id say its doing well battery wise. By 2 am at night or morning however youd like to look at it, its at 20% charge now. Oh and also after surfing the web or watching the videos on youtube, the phone doesnt heat up like how all other phones i have just start heating up like crazy. Toward the 20 min mark it got a bit warm but nothing to notice at all. I guess the quad core actually works like how they said about the low voltage or whatever to use less power and less heat. So thats a plus. Again the LCD is beautiful, i love it. Phone runs great, no problems thus far. As far as data and voice on 4g, i dont know if voice is on 4g on this phone, but when im on the phone i am able to use the internet just fine.