I haven't yet tested this product in the real world, but so far my thoughts are mostly positive. The general quality of the item is good, but it is very difficult to seal up the two seals in order to make it watertight.
Once you've managed to seal them however it is extremely good. I tried the tissue paper test as recommended on the instructions and it performed perfectly.
The only other problem I have with it is that it can be difficult to place larger devices inside, as the clear plastic is prone to sticking to itself.
Devices can be operated perfectly well, even on touch screen devices such as the HTC Touch HD. It is also possible to play music through your device's loud speaker which can be heard at near normal levels.