I download podcasts onto my 8520 and listen to them as I walk to work.
It is convenient for three reasons:
1) No wires getting in the way is the main benefit.
2) The multi-function button is on the head phone itself and so I don't have to ferret in my pocket to reach my Blackberry to pause the action.
3) Similarly, when there is an incoming phone call you simply push the same button, it pauses the audio file and you're talking.
The four surrounding buttons are impractical to use when wearing the headset because it is impossible to discern which button is which, although I did manage to turn the volume up one time.
To use the other buttons you need to take the headphones off.
Against the noise of a busy street it can be hard to hear an audio interview properly, so I suspect these are better suited to listening to music than interviews. Perhaps things are better when riding on the bus or the train?
Pairing them up with my Blackberry 8520 was straight forward, no problems here.
They feel initially a little tight when first worn but I quickly got use to the feel of them.
Overall, easy to set up and use, but perhaps not so great when there is a lot of background noise.
They work brillantly with my 8520, but they don't work at all with my netbook because I cannot find any drivers anywhere. The bluetooth dongle is fine. Why there is no driver for a netbook is anyone's guess.
2ND UPDATE (Sept 2013)
These also work well with my Blackberry Playbook. Actually they work better as it easier to find you music you want to listen on the Playbook rather than an 8520. Though it's necessary to uncouple the headphones from the phone first.