@zens My own set of e-ink design principles:

1. Persistence is free. Once set, the display will continue to show specific static content indefinitely, with no power applied.

2. Pixels are cheap. DPI is typically 200 or higher, devices well over 300 DPI are available, though not precisely common. This is equivalent to many laserprinter's dot resolution.

3. Paints are expensive. In terms of energy use (battery life), time, and disruption (display ghosting / flickering, varying with display mode), any screen changes impose technical or cognitive costs.

4. Refreshes are slow. Rather than 60--120 Hz, you're operating in the range of 0.5 -- 10 Hz. Most devices / modes can accomplish fairly rapid (> 4 Hz) updates, but that's not guaranteed.

5. Colors are very limited or nonexistent. There are colour devices, they're a small subset of the total, palettes are limited, and display characteristics worse than B&W (1/4 pixel density, slower refresh). Many devices offer a limited greyscale palette, ranging from 1--16 shades (1-4 bits). Line art works well, most raster images require dithering or halftones for best effect.

6. Pagination navigation is strongly preferred to scroll. Change the entire page in one fell swoop. It's much harder to regain reading point when scrolling in e-ink than it is with emissive displays. This means providing interfaces for paginated movement. Regions work better than gestures.

7. Reflective rather than emissive. You can't pour light into portions of your display, you can only remove it. Colour mixing is pigment, not light (if it exists at all). Readability increases with direct sunlight / bright ambient light. Many devices do have illumination (backlight / frontlight).

8. Touch / wacom may exist. Many devices incorporate a wacom layer and can use a stylus. Do with this what you can / may.