i've bought my 3rd one of these now, not due to problems but due to significant others nickign them!
bought for my iphone 4 on my 206, worked a dream, slight hiss if the power cable is connected and using radio...went on holiday to aus, took it with me, sister promptly stole it for her rav4 (she's using iphone 3)
came back, bought another one, mrs stole it for her polo...
bought final one (i hope) and using it for my new smart car with aux in, no hiss or anything even with power cable, clear calls, couldn't be happier with purchase! top product!
shows 50 quid + for a blue tooth kit that doesn't play music is a waste of time!
would be better if could select who you are calling but as long as you don't speak like a mong i find the voice calling (hold down the call button) on the iphone 4 works fine with this kit.
only other draw back is if you have it plugged in and either as aux in or tuned to specific frequency and you are listening to another radio station, it wont cut the channel for the call...not really an issue for me cos if i feel the phone ringing i switch to the right freq/aux fairly easily though.......