I've been looking for a compact cell phone holder for awhile. This one is exactly what I was looking for. Small size and capable of turning 180 degrees for gps usage with a simple twist. My iphone4 has an outside protector case, and this holder had no troubles holding it in place. For the price, this is the best bang for your buck. Under $5 and free shipping, you can't go wrong. I will be ordering another one for my wife's car.
If I were to change one thing, I would suggest shortening the height of the 2 fingers that grip the phone. I think most mobile phones are pretty thin these days, so the grips don't have to be so deep. I guess it's to accommodate older phones. But this is extremely minor design matter. No big deal. :)