eye fatigue... imagine when you stare at a computer screen too long, reading now... your eyes get tired from strain, you could get burning sensation, glare, dry eyes.. all this could lead to bigger health concerns.  Thats why e-ink is superior.  People have reported issues with led and sight.  If you want an ebook reader, the kindle,nook , and ereader are all superior for a hard core ebook reader.
links :
<a href="http://www.computervisionreadingeyeglasses.com/eye_fatigue_symptoms.htm" rel="nofollow">http://www.computervisionreadingeyeglasses.com/eye_fatigue_s...</a>
problems with led:
<a href="http://discussions.apple.com/thread.jspa?threadID=1677617&#38;tstart=0" rel="nofollow">http://discussions.apple.com/thread.jspa?threadID=1677617&#3...</a>