[dvhh]

For the main purpose that they are used for, displays that don't need to be updated frequently, like e-reader or "smart" price tag display.

However updating the display is more costly in terms of power than lcd.

We can also factor in that most e-reader also include backlight.

As a caveat, I appreciate e-ink technology, and the innovation that it brought us. I would also love to get my hand on one of those color e-ink android tablet. But I am not hoping to have a huge difference in battery usage from it, e-reader are very specialized device and can afford optimization that more versatile device cannot.