Could be the best, most streamlined app but...

...you cant play iTunes songs/playlists with this app running in the background. Songs are controlled from within the app so forget listening to your fav playlist, shuffling songs, listening to your audiobook, etc as YOU wish to control the audio--the app decides what you listen to.

Unless this gets fixed I will never recommend this app. There is no excuse for not having such a critical feature with an exercise app as most users will want to have music control whilst exercising.

*electrolite* about Intervals Pro - HIIT Timer, v1.1