As befitting a device which comes with free music, the Nokia Lumia 800 has one pretty useful feature first seen on the iPhone.
Unlike other Windows Phone 7 handsets, a user is able to control music playback, including play, pause, forward and back, using the single button on the Nokia headset which comes with the phone.
Using the headset, one click is for pause and play, two to go forward and three in quick succession to go back. Long press activates voice command.
The HTC 7 Trophy I compare it to only allows pause and play using the button, and the other two buttons on the headset controls volume up and down.
Interestingly the more expensive Nokia Monster headphones will also only allow volume up and down, but not music transport control using the buttons.