Addendum after a few days: Interestingly, the criticism has obviously helped. There are now cheap offers.
Experiences in the meantime: Mostly it finds what you're looking for. Some walls in the old building (113 years old) but nothing works, ie continuous alarm with full deflection (metal mesh?).
Often there are so false alarms caused by leakage or other faults, but with the device you will feel when drilling and nailing much safer than without these "electronic dowsing". Distinction metal / power works well otherwise.
Devices that operate properly, I have not found, this model is not bad. Very useful are the LED bars that show how far it has moved closer to a line. So far, no line drilled on our site.
Thanks for the tip with the pressed power button to turn off the annoying warning buzzer.
Otherwise: Would it, if I did not already have one, buy again