I enjoyed using my OLPC XO-1 for writing, programming, terminal usage, web browsing, etc. whilst sat outside on a sunny day. Was certainly a contrast to 'phone screens, which were barely visible, even with a backlight and shielded under a hand!

(The XO-1 uses a different display technology to these e-ink monitors, but the result is similar: a high-resolution greyscale display, lit externally)