It's an interesting hack. I do wonder whether or not it's a little over-engineered. When you look at the costs of all the kit versus maybe an older OLPC type computer off ebay I'm not sure how well it stacks up.

Then again, it's probably pretty good in sunlight and despite the refresh rate issues considering idle time in an editor it might be a very good use of the e-ink screen. And as I said, it is a nice hack. Certainly better than most raspberry pi posts I've seen.