Jason Kottke on the new rules for reviewing media:

Compare this with traditional reviewers who focus almost exclusively on the content/plot, an approach that ignores much about how people make buying decisions about media today. Packaging is important. We judge books by their covers and even by how much they weigh (heavy books make poor subway/bus reading). Format matters. There’s an old adage in photography: the best camera is the one you have with you. Now that our media is available in so many formats, we can say that the best book is the one on your Kindle or the best movie is the one on your iPhone.

Kottke is right, of course. In time, online reviewers would begin to take into account which version – Kindle, iPad, or Nook (or whatnot) it is that provides a better reading experience. And perhaps that answer would be different for different kinds of books.