So another company is getting in on "back of phone detachable ereader" like xteink. I'm a big fan of my X3, but the act of having it attached to my phone is not great. Can't use the included folio case and have it attach to the phone. Once you do attach it, both sides of the brick have a delicate screen, so extra odds of smashy smashy. It's not great to use while attached to the phone, I just store it there and then remove it from the phone when I want to read. It would be more interesting to either go for extreme thinness, maybe only enough batter in the eink reader to last an hour, but it charges off the phone. Or just let the magnets attach it with the screen against the phone. Book doesn't seem like they're really doing anything interesting here, vs what xteink already does for less