It is a highly recommended simple tool to verify signal strength. I works very well. I am adding it to my app toolbox of network apps. Particularly like the sound/beeping feedback and the spot log/recording features.
Im only using the free version. Maybe the paid one has additional features, but it would be nice if additional information was displayed i.e. Wifi channel, ssid, etc. for environments with multiple APs. Even without those the app is useful in detecting areas with poor coverage.
Cosmicboss about Wi-Fi SweetSpots