You have to hold the phone horizontally while shooting, and at the moment the video is limited to 3 minute lengths (though that will reportedly be fixed in a future update.)
It's $79, and available in four colors!
TechCrunch: Quick Review: Kogeto Dot Panoramic iPhone 4/4S Add-On
Luckily, the Looker app is due for a pretty significant update, which will include nixing that 3-minute max. I see anyone who travels a lot falling in love with this product, as you really won’t miss a thing shooting with Dot. In fact, anyone who enjoys mobile video or has an ounce of creativity can probably get a lot out of Dot, and it’s one phone accessory I’d actually recommend.