Product review (2 stars): So far, only works part of the time.
Seemed like a good idea, but only worked for 3 or 4 days. Couldn't get it to reconnect to the iPhone app. Phone showed it connected for a couple minutes, but wouldn't stay connected. I only gave it 2 stars because I like the idea. Otherwise, it would have been 1 star. It is nice and small, so doesn't take up much room in the case.

Decided to order the "Oasis OH-2 Digital Hygrometer w/clip" and just look inside the case when I want to check the relative humidity.

Edit: Well, it started working again after not working for 4 days. I raised the stars to 3 while I see how long it works.
12/26/2017 Well, it quit working again for the last 3 days.