Do you read faster or slower on a device like an iPad or Kindle, in comparison with a physical book? The overall answer, according to usability expert Jakob Nielsen, is about 5 to 10 percent slower (with the same comprehension of what was read). That's statistically significant, though not all that much slower. (We suspect it may have to do with years of familiarity with the form factor of the book.) More interesting was that on a 1 to 7 scale, users rated their satisfaction at 5.8 for the iPad, 5.7 for the Kindle, and 5.6 for the physical book, with the traditional PC trailing behind at only 3.6.