I have two of these sensors. One at a house, another at a business in another town in case a water heater leaks.
I did not have any trouble setting them. You need WiFi in each place, of course. The battery life has been good. After 7 months, both are still working and show high battery level. The iPhone app works fine and I have it setup to send me a notification if it is triggered, so no need to even consult the app or have the app running beyond initial setup. I give it four stars because the iOS app is slightly klunky.