He does what is expected of such a product: ringing phone -> Quick Release push of a button.
Having a Nokia Lumia, the kit is compatible with voice command. I can and who I want to call using the voice command of my phone. That said, a phone without voice control will not be practical since it will touch the phone to call ...
I therefore recommend to also purchase a car mount for the phone, which I did. The kit does not have a display screen, you will not know who's calling without touching your phone ... which goes against the principle of hands-free kit.
So, in conclusion I would say that this is a very satisfactory product and that I find very affordable!