4" screen and 16MB flash is a joke. Ebooks are small, but not that small. Considering how many used, end of life Kindles there are out there stuck on old easily jailbroken firmware, I don't see why anyone would ever choose this as an alternative. The software for jailbroken Kindles is incredibly mature and at the point of "just works". E-ink technology hasn't progressed much in the past ten years, so you really don't miss out on anything by buying a $30 used one.

Edit: just realized it has micro SD support. So my storage concerns are invalid. It's still incredibly clunky looking though, a 1cm thick device with only a 4" screen sure is something. My eyes probably couldn't handle it even with the largest font.