I've got that same Kensington thing on my desk right now, and it's a piece of crap. For starters, horrible ground loop. To be fair, Kensington mailed out a filter which took care of it, but the TuneLink I mentioned up thread has the filtering built in. Still though, the sound quality just wasn't that good, and it would randomly fail to work.

The bigger problem for me is that the Kensington device really wants to do the handsfree and A2DP protocols, and I already have handsfree in the car. The Kensington has no option to not do handsfree, and the iPhone doesn't have any way of saying "yes, I know this paired device supports more than one protocol, but only use A2DP with that device". So, I ended up having it connected to both, and they fought each other. I could have just given up on the handsfree built in to the car, but that would be stupid since the Kensington mic was so terrible, and it's mounted right on the part that sticks into the lighter plug, which in my car is in the center console.

So, I threw it into the corner of my office, and moved on to two or three other similar devices before landing at the TuneLink.