Tallguy we have the reciever on the Garmin 2820 in the car and it is pretty good saved me being stuck in nasty traffic a couple of times when the M25 was closed for hours. In London however the roads are pretty bad most of the time so we only use it on longer trips when we head off away from London.
Not so sure how useful it would be on the bike in normal heavy traffic because a bike can filter it may only be really useful if the road is closed altogether.