THE BEST.

Clear sound. Wonderful variety. Ambiance for every situation in my life (e.g., reading, sleep inducing, quiet background, entertaining, etc.)
Only drawback I have encountered is when I upgraded my Iphone, my purchased tracks did not migrate with me. I contacted customer service and they responded with a short generic note that was slightly helpful.
The app still gets 5 stars. The help desk? Not so much.

KZs Gramma about Naturespace: Relax Sleep Dream, v5.1