I bought a Kindle e-ink years before iPad, and I still keep it even though I rarely use it now. I figure it's great for battery life in case of electricity outages or limits. Other things I really liked about my old-school Kindle: The page-turn buttons meant no accidental page turns, and the keyboard on mine gives a good place to hold it comfortably. I didn't like paging thru among my library or using a clip-on light, though. The old-school ones also had sucky contrast.
My eyes don't bother me for extended reading on backlit devices, but I'm careful with the backlighting staying in balance with ambient light, get annual eye exams and have lucked out so far with good eyesight. I also am careful to limit full sun exposure to protect my eyeballs from cataract risks and such, so I don't ever read in full sunlight.