To make the text larger than 10-point font requires zooming in on the document and dragging it around with the iRex's stylus, a naggingly slow process given E-Ink's refresh rate of about one second. iRex claims it redraws its screen faster than Kindle, but in Forbes.com's tests it locked up sporadically and often took far longer to refresh than Amazon's less flashy display.

FORBES: E-Books

Then again, when we wanted the sensor to kick in, it would do so only about 60 percent of the time, and again you'll see the effects of slow page refresh times of E Ink.

ENGADGET: Amazon Kindle DX Graphite review

Given that this is an extremely early prototype, the E Ink device had a lot of bugs when we played with it: force closes, reboots and slow response are among the things we noticed.

ENGADGET: E Ink reference phone and flexible display hands-ons (video)