First, of all, the test. After installing the App, there are no instructions on how to get it working, and no help on the VeloSoft web site. Eventually, we figured out that when you open the app, your iPhone shows up as a device in the finder, which you then can "connect to" by clicking on a pop up on your iphone.
After you do this, you can transfer files by dragging them onto the iPhone device in the finder, just as you would any other device. You can create up to 12 "volumes" (ie: folders) to store these docs. and you can transfer them back from your iphone to the desktop just as easily.
The big problem is that the DataCase app must be installed on both the computer that you are transfering from and the computer you are transfering the files to. This severely limits the ability of the storage mechanism. Thinking about taking those files with you on a business trip and then downloading them back on somebody else's computer? Not likely.
Still, its nice that there is some way to store PDFs, videos, audio files, excel files and text files on your iPhone for mobile viewing / listening. The app works smoothely enough, but its still in a very early (beta) stage.