Does it or does not keep them?

I have read a lot of positive and negative reviews and was afterwards so smart as before. Does the holder delivers what it promises or not? So try ...
I drive a BMW E46 with nubby and sloping dashboard and have a 5 inch Navi. Conclusion: The bracket is tight despite slight swing. The Navi has thereby withstood a screeching halt and many kilometers of very bad road without complaint. At first I was a little irritated that the holder does not stick, but only lies, but the system works. Genial that the entire Navi incl. Holder you can make them disappear from the visible range of the car with a handle, without leaving a trace.
Useful for other interested parties is mE a positive-negative-list at even following reviews. So please make and model name.