The first data I look for when I read these enthusiastic reports of color e-paper screen is the refresh rate, and every single time the results are discouraging: 15 seconds for refreshing a page make the product nearly useless for almost all purposes except maybe calendars, but the inferior graphics quality and higher cost make them a lot less appealing than for example using a normal LED screen plus a PIR sensor that turns it off and sends the CPU to sleep when nobody is around to save power. I think the technology just isn't there yet, and will probably need a long time before it becomes interesting for practical uses beyond tinkering and research.