The korean implementation, DMB seems to work amazing well. So well that people in seoul can travel for over an hour underground on the subway and not have a glitch. The system here is as Azayzel described, its not an individual stream to each handset, but the phone tuning into existing digital TV broadcasts.
I've even seen one or 2 handsets that I believe can tune in to satellite TV.
Its still unnerving seeing people wandering the streets watching TV while walking. Still, would be great for watching sport so you don't miss anything.
The phones themselves are certainly no larger, and probably smaller than most of what is available in the US (the newer ones here that is).
Unfortunately the korean system is developed in korea, and hasn't been adopted anywhere else in the world, so while they've had this tech for quite a while and are still going forward, its not applicable to anywhere else
