I did 3 times just to see. I had a bit of a harder time reading on my netbook screen, but I did get all three answers right each time. I had I think it was 550 or so words the first time and the other two in the 520's.
Of the books I had only read one to compare, Wuthering Heights. It said I think 3 hours and 20 minutes which seems about spot on. I think I might have read it a tad faster.
I read a book in about 4-5 hours at leisure speed. A full book that is with 350-450 pages and so. Sometimes faster, sometimes slower. Just depends. Sometimes I plow through one in 3 hours when I just can't stop turning the pages.
I do know that I have a much easier time to read on e-ink with my eyes than on the computer screen. Even such a short text makes my eyes all wonky.
