Have used for a few months now. I noticed subtle changes to my 6+ battery usage - can confirm this has consistently been at top even when not running. Under usage it says "background app usage" for this app - but there is no tie-in to the background settings page where you should be able to disable this. IMO that is worth 3 stars, because our batteries are more valuable than your apps background usage even when not running.
That said - the app does technically work (though the interface could stand some refinement and art direction).
Drywall Masta about Baby Soothe, v1.9