The ability to quickly start the run (even using Siri) is outstanding; however, the aspect of the app I love the most is the guided runs, especially the Headspace runs with Andy Puddicombe and Coach Bennett. The ease at which they start the run is absolutely perfect; however, it is the wisdom and knowledge they drop on you throughout your guided run. I have used their advice and applied it to my own like, be it at school or at home with my wife and 2 children. I am forever grateful to them both.
Embedded below is a 2 minute and 36 second YouTube tutorial.