Yota Devices: The YotaPhone Android smartphone sports two 4.3-inch displays. The main screen on the front is a LCD with a 1280×720 pixel format with a resolution of about 342 ppi. The back screen is a 640×360 electronic paper display (EPD) with 16 levels of grey.
I can make good use of this. The only, and best, use of the EPD is to read text; most other uses detailed by Yota Devices are gimmicky. I read, a lot, everyday and most of it is on my iPhone because the iPhone is almost always with me, but my eyes get tired reading on the LCD. If instead I could read on an EPD — text only and stripped of all the chrome and ads — I think I would enjoy reading quite a bit more.