I searched the internet for about two weeks before coming to the conclusion that this was the perfect iPhone mount at the perfect price point. Disregarding the handful of reviews that faulted the product for not being secure enough (I decided that they just didn't know how to properly mount the thing), I went ahead and made the purchase on August 15th. I must confess that I didn't get around to installing it until ten days ago.
The mount appeared to work as advertised, although there was a slightly rattle of the iPhone 4 on rough patches of asphalt. It and held onto my iPhone 4 decently for about four days, which was unfortunate because that was just enough time for me to start believing that this mount would continue to work well for...perhaps it lifetime warranty!
On day four I hit a small crack in the pavement and the mount sent my phone flying off. The phone skidded across the asphalt upside-down for about 30-40 feet like a hockey puck on ice before coming to a stop. I examined the phone and was surprised to find that while the edges and the surface of the touch screen were scratched, the phone itself was in working condition and the screen was not cracked (as happens in so many of these cases I've come to find out). I'm still not happy about having a scratched up iPhone. The mount itself is still in working condition, but I don't know that it's worth the trouble anymore.
That being said, this all leads me to seriously reconsider using this product. While the fit is good and the phone generally stays in place on very smooth rides (on fresh asphalt for instance), as a an avid bicycle commuter I cannot see how one would expect this product to work well for an extended period of time. Not only does it NOT hold on very well to the iPhone 4 that it's advertised to work with, but it requires the removal of a protective case. Removing the protective case makes the iPhone 4 rattle slightly over rough pavement (not gravel or dirt, just a typical city street) and it also means that the iPhone 4 is very susceptible to damage should it come loose.
I still have it on my bicycle for now and when I need to use it I strap on some heavy duty rubber-bands (the sort that hold your broccoli together at the grocery store), but I'm already looking for an alternative and I'd recommend that you do the same.