I have used another 2 types, and liked them, but I would personally say that is risky. I would add in those pellets you can put in the bag with the iPhone, as I do for mine. But be aware none of these are 100%.
also you will see some degragation from shooting thru a bag, essentially. low light, etc.
I recommend the new Nikon and the olympus, both about $300. but even those are not 100% either - I still put my olympus in a wet suit bag. :)