I like it.

I havent had any problems with the app and Ive used it for almost three weeks, though not consecutively. I tried two other similar apps in the intervening weeks & have decided to go back to Pillow. It syncs to other apps I use such as the health app. I also like that it offers a watch app. Ive only used it once though. I like the variety of alarms it offers as well as the various sounds to help you fall asleep.

nnsmith about Pillow: Sleep Tracker, v3.0.4