I've put together a quick comparison of the same document (a page from a sample chapter of a technical book in PDF format) being displayed on a Sony PRS-T1, an Apple iPad 1 and the new Ectaco jetBook Color. You can find it here:
http://jetbook-color-comparison.pen.io/ but the tl;dr version is shown below. For reference, the Sony is a 600x800 6" screen, the iPad 768x1024 9.7" and the jetBook Color a 600x800 colour, 1200x1600 black and white sub-pixels (it's complicated...) 9.7" screen.
Andrew