I, too, was surprised at the rather short battery life. The estimates you hear are clearly from the marketing folks.
Three things to do that will help:
1 - Keep the unit in "Airplane Mode" unless you're actually using Wi-Fi.
2 - Turn off auto-brightness for the LCD screen and set its brightness as low as you can manage with. I've found that 10% is easily bright enough.
3 - Set the timeout for the LCD screen to 10 seconds.