Same experience here: very disappointed at first by the greyness of the screen of my BeBook. But since there will not be any better scree in a small device for the coming months/year, I chose to adapt: I bought a daylight bulb: 6500K, 1200 lumens. It makes the screen whiter than regular light bulbs. Sunny days also make it whiter than cloudy days. Next spring/summer, I am sure I will loooove this screen!
Besides a whiter screen, I also want it to offer 300 dpi. 160 dpi are not enough with many PDFs even in ladscape mode.
I also want the format of the screen to be 16:9 or 16:10. And 7 inches in diagonal, not 6. It would help a lot when trying to read PDFs. All that without the device being bigger, of course.