Ordered this item off the back of a review I read on here stating it was really good.
On receipt of the item it has been in my car & used every day (July 2011-September 2011) to hold my iPhone while it is plugged into the stereo via headphone jack.
I have used it to hold my TomTom in place & not once has it slipped off (unlike a few times when it has been stuck to the window) - it is also out of sight when driving, i.e. not cluttering up the windscreen.
I recommend this "Car Organiser", for want of a better name, as it beats phone holders on price, size, convenience (you can remove it & store it in the glove box in no time), ability to do more than just hold a phone, etc...