Alone, this device doesn't sound like much, if anything. To connect to the internet, it needs to use a Blackberry. While details are few, I suspect this will be marketed as a device that will turn your Blackberry into a tablet allowing you to do some decent web browsing, ebook reading and video watching on a large screen. It would also be better for email triage, though unless there a keyboard option, I am not sure if composing emails would be better on a virtual QWERTY keyboard on the tablet or on the thumbboard on the Blackberry itself.
This isn't anything new. The Celio Redfly has been out for a few years and starts at $199. It has a mini-laptop formfactor rather than a tablet and was designed in an age before people considered putting capacitive touch capabilities in large screens. The Palm Folio was similar to the Redfly, except that the Folio never made it to market.
The question is, how many people think a large screen is must-have accessory? For most tasks, it won't allow you to leave your laptop behind for any but the shortest of trips, so this is an extra device to tote around, not a lightweight replacement.
Two or three years ago, a companion device had some appeal, though it was so limited there was no real commercial success in them. Today, it seems like a me too effort to make it appear you are keeping up with everyone else's tablet ambitions. Would you be willing to buy a companion device like this?