It's really cool. Information should be as cheap to access as possible and the platforms for doing so should be available to all.
I will say that there are two factors I look for in a reading experience that might need improving here.
The first is ergonomics. If I'm going to be holding an object for about two hours a day, every day, then it needs to feel good in my hand. This model looks a little chunky and unfinished. As a proto-type that's fine, but whilst you shouldn't judge a book by it's cover, it helps if that cover isn't made out of sand paper.
The second is the font. That's the bit that gets the text from the page to your eyes. Typesetters and typemakers have spent an awfully long time figuring out what fonts work well for reading, and I don't think the font being used here is one of them. Also, folk have different requirements for fonts. Can that be changed by the user?
There's also the issue of format. Right now it appears to only support plain text files which is odd because isn't epub an open format and a pretty good standard?