Upon launch, DataCase's screen provides you with a handy donut-shaped graph that breaks down how much capacity is being used by different types of files you're storing in DataCase; it also provides a text breakdown below the chart (it doesn't, however, reflect how much space your iTunes-synced media files are using, for example). And not only does DataCase let you view files in landscape orientation, you can also flip the phone to navigate DataCase's interface lengthwise as well--helpful if you have long file names.

DataCase allows you to create multiple volumes, each with their own read and write permissions, which is handy for power users, but has the potential to confuse beginners--for example, there's no way to copy a file from one volume to another on the phone itself and there's no way to search all your volumes. By default, one volume is set up as a Drop Box that other users can put files in but not read, and another is set up as a Shared Files volume that all users can write and read to.

I found DataCase's interface to be the least intuitive of the three; for example, from the main screen the only option, is to tap the folder icon in the donut hole, which isn't obviously a button. And while a Filter button lets you choose to view only a certain type of files (audio, video, pictures, and so on), it doesn't provide the same name-searching capabilities that Files has. Plus, due to the subtle nature of the UI when you're filtering, it's easy to forget that you're hiding some of your files.

When in file viewing mode, DataCase adds toolbar controls that let you jump to the beginning or end of a document or page up and down. However, of three apps tested, DataCase had the least support for different file types. I would frequently found myself confronted by an error saying that the selected document could not be displayed. I also ran into an issue where any attempt to transfer files would crash the program, but reinstalling the app seems to have fixed those problems.

The final entry in this trio of utilities is the least expensive of the three, Magnetism Studios' FileMagnet. Unlike DataCase and Files, FileMagnet foregoes the use of the networking protocols built into most operating systems for a free desktop-based application called FileMagnet Uploader, which you'll have to download from the company's Web site. (The first time you launch FileMagnet on the iPhone, the app will prompt you to do so.)