[protheus]

Don't know about Kindle but I tested (preproduction model) for a few weeks a Evolio reader, it's the same thing, but another producer. The screen really is ink like, very "easy" on the eyes.
Battery was charged when I received it, and still had some energy left 3 weeks later, when I took it back.
For reading what can I say, you can't beat it, except with the real paper of course. But for that paper a few trees had to come down, so I prefer something like this, reusable and recyclable.