The power button is tiny and flush with the case near the back,I find, making it impossible to find by feel. This button also operates the microphone 'mute' function and In my opinion would be nearly unusable while driving. I didn't find the instructions very clear or easy to follow. Excellent audio quality and intelligibility at both ends. Lots of volume is available if you need it. No sign of the 'direction switching' which afflicts some handsfree units and cuts off people's words. Very long operating time on a charged battery, which is easily replaceable. Very easy to install and get it working.

If you have a Bluetooth-enabled mobile phone and you drive, this is an accessory you really should have. Highly recommended.