That much is understandable. Yet many of the comments make it clear that there are a couple of qualities that dominate people's concerns, yet they aren't a part of the poll. Perhaps an "Other (please explain)" would have been appropriate in this case.

Perhaps the question could have been rephrased too. Something like "What is the most important quality that you use to differentiate ereaders?" This allows people to suggest the most important quality they used (or would use) while selecting one reader over another reader. Let's face it: most readers have a similar feature set, and only differentiate themselves significantly in a couple of areas.