It’s just one screen with multiple modes - a bright full color LCD, reflective E-Ink black and white quality, and transflective LCD mode. That’s pretty damn amazing if you ask me.
The Pixel Qi screen while in eReader mode has a lot of pluses - Black and white with 64 shades of grayscale. It’s reflective so it works in sunshine. It uses very little battery power in black and white mode. The full-color mode of Pixel Qi screens is like an LCD screen. It even does what no other e-Ink display can, plays videos and full color photos. You get everything you get with a regular LCD screen, just the lower power and higher-resolution of an e-Ink display. Pixel Qi won’t reveal yet how many nits when running at full brightness, and although it won’t win any illumination awards, it’s plenty bright. How it handled motion was a bit harder to gauge, when turned, it immediately switched to the electrophoretic reflective mode—where backlighting is replaced by ambient light reflecting off the back of the screen. In that mode, it is just as crisp as the Kindle for reading text. You can watch video in this mode too, though it’s not exactly pretty (the point being you don’t have to wait forever for the screen to refresh when you turn a page). They wouldn’t speculate on how much battery life improves when you turn off the backlight, simply stating that it saves you 2 watts of power.
They’ll be able to produce different sizes, for different form factor devices, meaning we should see them in a lot of different things over the next year or so.