Argus is the first app to officially take advantage of the new M7 motion coprocessor found inside the iPhone 5s. As the floodgates are open now, small wonder fitness software makers are scrambling to update their warez with support for the power-efficient chip.
If you own an iPhone 5s, it's already tracking your movement on a daily basis so M7-compatible apps have a history of what iOS has already recorded to work with.
You can now add David Smith's Pedometer++ to your list of apps which take advantage of the M7 rather than dutifully perform motion calculations day in day out using the power-hungry A7 processor...