I was looking up the specs on the Jetbook for a friend and noticed the comparison below on their Specifications page where they list attributes of the Jetbook, the Sony eReader (PRS-500), and the Kindle (1). I guess if you don't have the latest technology you have to find some way to slam those that do, but this seems like a stretch:
Jetbook column: Screen characteristics
Immediate page turn (screen update) without any flash or artifacts. Very good contrast between very light greenish background and black letters. Eyes do not get tired
Sony column: 1-1.5 sec page turning time (screen update) through black and white "splash" on the screen. After 40-50 pages of reading, eyes get tired due to this effect. Number of artifacts from the previous page left on the next page, causing "dirty" marks.
Kindle column: 1-1.5 sec page turning time ( screen update) through black and white "splash" on the screen. After 40-50 pages of reading eyes get tired due to this effect. Number of artifacts from the previous page left on the next page, causing "dirty" marks.