In Leo's last review of the HTC One, he mentioned that he sometimes couldn't get through a whole day on a single charge with the HTC One. He tried getting a replacement unit to test, but he got the same results. Leo suspects that the poor 4G/LTE reception on AT&T in Petaluma could be partly to blame, since others are getting better results. He also can get much better battery life when he uses it in airplane mode or with just Wi-Fi, which is another indication that it's from the phone searching for 4G/LTE. Searching for signal is one of the most demanding things on a phone's battery. Aside from this battery frustration, Leo loves the design and build quality of the HTC One.