Compared to the printed book reading speeds were 6.2% slower on the iPad and 10.7% slower on the Kindle 2. Nielsen states in his findings, however, that the difference between the iPad and the Kindle is not statistically significant. You can read just as fast on an LCD as on an E Ink display.
Other interesting findings:
…they disliked that the iPad was so heavy and that the Kindle featured less-crisp gray-on-gray letters. People also disliked the lack of true pagination and preferred the way the iPad (actually, the iBook app) indicated the amount of text left in a chapter.
Less predictable comments: Users felt that reading the printed book was more relaxing than using electronic devices. And they felt uncomfortable with the PC because it reminded them of work.
The Kindle 2 sports a 16-shade capable greyscale E Ink display. E Ink and Amazon will most likely need to increase the Kindle’s grayscale capability to 32 or 64 shades in the future.
I also think reading the printed book is more relaxing, especially if the paper quality is good. Is it just me thinking this or is quality of paper used in printed books generally going down? I don’t mind paperbacks using crappy paper but when I invest in a hardback I expect paper quality to be good. And yes the iPad at 1.5 pounds is a bit heavy to be used as an ebook reader if you plan on reading for quite some time, unless you have a bookstand for the iPad.