One thing to note, this is _not_ an e-ink display. The quotes around e-ink should be replaced with "diaplay that looks like e-ink" There are no colored capsules in this screen which float around to create a picture. These are usually just regular LCDs with no or little backlight and a reflective backing.
Transflective displays do seem to result in decent battery life, the Pebble Time watch is a good example. Though we do now have long lasting OLED watches – looks like running Android on a beefy CPU vs a tiny RTOS on a microcontroller is the bigger difference… buuuut still the Pebble gets away with a smaller battery than these OLED ones I think?
Same as running the laptop with the brightness all the way down (Windows) and backlight completely off (Linux). This is specific to the X230.