I wasn't impressed. Got one at a great price...free...and felt ripped off. That may be a bit harsh, but I got in my car with the unit and let it find a station to use. Used it and got excessive fuzz. Let it try again, same problem.
Then I took the other route. I manually tuned through my FM radio to find a totally unused station..not even any bleed from those around it. Tuned to that station on the Zune FM doohicky and still got unacceptable hiss.
Granted I only tried this in one car, so the radio may have something to do with it, but in normal use the radio is fine. If I can't take a random car and have it work acceptably though, it's a failure. Couldn't even say, 'works for me, YMMV'.
Who knows, somebody, in some car, travelling across Kansas on I-70 may have better luck. Maybe in Canada you would have better luck. You guys have radio stations up there?
It is a well designed piece of kit though. Two cables from the accessorery plug, one to the Zune, one to the controller, which has a great little magnet so you can stick it somewhere. Designed for the end of the plug, put if you have metal in your car, it would stay there. To bad functionally it is lacking.
I also have a Belkin TuneCast II that I got a long time ago. It is significantly better, but of course it doesn't have the nifty control capablity.