As others have mentioned no flaw. This is the whole point. You don't get eye strain from reading a backlight screen. No e-ink have backlight. One Sony device had some sort of side light that people said was terrible. You have to get a clip on light that is either battery or USB powered to improve your reading experience in low light settings. Yeah I will get slammed for this but understand the technology before you purchase!

That is the on going debate out the iPad vs Kindle, eDGe, blah blah blah. Short term reading LCD is fine. Book reading for most people it is a poor experience. On the eDGe you have the choice of doing either.