The screen is continuously on, and runs on very low battery supply (I'm guessing from the iPhone). The screen displays impressively detailed images of your own choice. Something to look at when you have your iPhone face down on a table...at first this sounds a little pointless. But with the photos and the video demo, the result is surprisingly impressive. It could be a nice effect to have a case that acts like a slideshow, making your case continuously changing...the case would never get boring.
The device isn't available just yet, the company are raising money to kick off the product, below is an embedded link to donate money. I believe the product will only be available on the iPhone 5, I am presuming they are planning ahead for the foreseeable future of iPhone.