I think maps are useful when choosing your destination, but when navigating the city streets, orienting yourself by finding landmarks on a tiny screen can be tricky. I like this idea of having a pointer, a directional compass that at least tells you you're heading in the right direction.
I like the concept behind this app. I could have used something like this a couple months ago when I ended up parking several blocks away from my destination (yay city parking). Maps got me close to my destination, but the walking directions didn't quite follow the walking paths available and it's semi easy to get lost in your phone instead of paying attention to your surroundings. Crowsflight shows you were you should be looking for your destination, features a quick search feature (useful when stuck on slow 3G), and built-in maps as an additional way to find nearby points of interest. It's one of those things where you ask yourself why you need another compass, and end up realizing that it can be super useful when smart features are attached.
You can download Crowsflight for free from the App Store, and unlock all of the features for a dollar via an in-app purchase.