The operation semi-works and has a nice GUI, but the pop-up ads cause the app to crash. Upon start-up, you get “ad starts in Xx sec”. 50% of the time, the ad doesn’t start, the screen is grayed out and controls are locked. The app does however basically continue to detect. If you survive the boot-up ad, another ad pops up a short time later. If you ‘X’ out of that ad, the app will not return, necessitating a restart of the app (and dealing with the boot-up ad). When the app did work, it appeared functional on metal items ran across the iPhone magnetometer, but I could not keep the app running long enough to test for wires/nails in a wall. I was going to purchase the no-ads version, but I’m not certain the app won’t keep crashing. With some developer debugging, the app would show promise.