It wouldn't be a good e-reader because it's backlit. Take a look at a kindle or one of the other e-readers with e-ink. The e-ink isn't backlit, it isn't being refreshed, it is very enegery efficient (battery lasts forever), you can read it in the sun. It's as easy on your eyes as reading a piece of paper. Plus the other e-readers cost anywhere from $60-$300.
You can already read your kindle books on your iphone or ipod touch, and I'm sure Amazon would come out with an app for that for the tablet.
To expand on the e-ink, I can't find the company website but there's a company who's already developed coloured e-ink displays.
Found it:
http://www.mirasoldisplays.com/ereader/