I did noticed that when I first got mine, the battery life was pretty short but after the first few days, it stabilized, and now it's pretty good. Not great, but pretty good. I leave Hey Cortana on, and use the phone for music playback, plus the usual stuff - messages, email, etc. Occasionally I'll use it for GPS, but that tends to run the battery down. I have found that if I don't manually shut down all the background tasks that build up over time, it gets warm and burns more battery. So when I want to put it away in my pocket, I'll hold the back arrow and shut everything down first, this seems to make a difference.