@ashan Battery life has not been an issue I usually go the whole day of heavy usage in one charge... , but you are right having extra batteries will give you much usage.
Hard question considering I really don't like or use the kindle/Google reader. I prefer Moon or Mantano they are far better. However I did fire up both Google books and the kindle book reader for you.(they come pre installed). In short they look good. If I did not already use Moon I would be fine reading on those apps.
If your question is reading on a five inch screen the answers is just fine. The screen res is better on the note than the eInk devices so the font is crisp. Also the contrast is much better which also makes it easier in the eyes. That is my experience from my eInk devices don't folks might have a different experience.
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