First of all the Higher Resolution enables 1:1 ratio playback of 1080P movies
Old Display: 1680x1050, new Display: 1920x1200. In desktops terms 20" monitors are 1680x1050, and 24" monitors are 1920x1200 - So the new display allows you to have the same amount of Windows open as a 24" display.
More windows can be open at once in full view (Until we get Resolution Independence 😛).
The LED backlights use around 30% less power then conventional display lighting. And the LED's are instant-on at full brightness while the previous display technology had some warming up time after just being turned on until they reached full brightness.