I am using this and its passive version in two of my guitars in which I do not want to use glue for installation. After having tested multiple transducer/undersaddle/... pickups (including Trance Audio, various LR Baggs, the Ultratonic, K&K, ...), I have to say this is overall my favourite when considering tone and ease of installation (and deinstallation). Adding a microphone or a magnetic pickup, the tone one gets is imho very close to the real thing.
However, both of the HFNs I bought from Thomann stank disgustingly of cigarette smoke. In fact, they stank so bad that I had to immediately throw away the paper and foam packaging, and my wife still noticed the smell of cigarettes in my room (we are non-smokers). What gives, Thomann? Hence, only 4 stars.