Buggy. inconsistent in the way it works through car's Bluetooth. Randomly stopped giving audible ringing when on incomming call. Microsoft is constantly bigging itself up as it releases new (and pointless) features for this product constantly when they should be going right back to the start and fixing the core & most basic functionality that doesn't work properly. For example, when adding someone to an existing call, why can't you cancel/hang up on them before they answer?