The app is surprisingly well-featured. I was kind of expecting little more than a recruitment app, but that's really not its focus. It's more about offering access to the official U.S. Army site and blogs, the ability to listen to Army Podcasts directly on your iPhone or iPod touch and a chance to learn basic information about the Army.
One of the more interesting sections of the app is its Fact Files area, which lets you learn about the types of weapons, equipment and vehicles that are used in the Army and how they are utilized. If you're interested in military garb, it's pretty cool.
The interface is pretty slick and the app offers the ability to download for offline access. Honestly, this is a really good example of how to make a quality iPhone app for a website that both complements the actual site and also offers some additional mobile-optimized features.