As processors and displays get more efficient, the need for larger batteries decreases. The GS6 has more energy efficient display and processor and due to the thinness of the device went with a smaller battery. I would have been happy with a slightly thicker device for more battery which would still be small. I am able to get through the day without exhausting the battery but all that depends upon carrier networks and user habits and setups. Also, for those not updated from 5.0.2, there may be other issues affecting battery life.