I've had the nook for two weeks and the battery life is not too impressive. It is 1.4 firmware and I charged it via the wall outlet. The battery drains at a rate of 6% per hour in reading mode with airplane on and display set to the lowest. With WiFi on, it drains at 20% per hour. Even in sleep mode, it drains at 1/2% per hour. Turn off and on takes 3% of the battery.
I now leave the unit turn off at night. I turn it on after work and read an average of 2 hours per night with bare minimum occasional WiFi on just to download the books. I need to recharge every 4 days. This is manageable since I bought the nook for travel so as long as I get a full day of heavy usage per charge (assuming 2 hours WiFi and 8 hours reading), I'm ok. I have outlet at home and I can always get to an outlet at the end of the day when I travel. However, I am annoyed that even in sleep mode, I'm not getting the advertized 10 days battery life (at the rate of 5% drain per hour, it'll discharge entirely in approx 8 days).
I love my nook but the battery life could be better. I am also wondering if there is a bug in the 1.4 Firmware that is causing the battery drain. Hopefully B&N can fix it.