The walk is a fun game that will more than motivate you to get off your couch. The voice acting is decent and the story is exciting enough to keep you entertained.
On a technical level, theres bound to be visible battery drain on any app that uses GPS as often as the walk does. As a 5S owner, its nice that the app apparently makes use of the M7, but wouldnt it make more sense to allow the 5S to simply not use the GPS at all and rely solely on the M7 step data?
Either way, if youre used to running and walking apps the battery drain wont be a hurdle for you to get passed.
Otawong about The Walk: Fitness Tracker Game, v1.0.1