When I first decided on getting one of these I was looking for something more expensive as I thought they'd be better, however I read the reviews on this product and thought I'd give it a go. It really is a great product. I was concerned, like every buyer probably, that it wouldn't hold my iPhone 4 tight enough but I felt confident with it as soon as I started running - there was no way it was coming out unless I stopped to unstrap it.
I was really surprised by the touchscreen too - I honestly thought the plastic cover would lessen the sensitivity but it worked great, as if there were no cover at all. As I think someone else has already said, I don't reckon you could fit a key in the provided slot but I have a swipe card anyway (which I just tucked behind the phone) and the slot makes for a good enough cable tidy. There was no rubbing or irritation which I saw mentioned on a lot of the more expensive versions of this product.
Overall, I would definitely recommend this product to a friend. It's cheap, reliable, looks good and the seller was prompt with delivery.