as introduced on the weekend, the Griffin armband fits to the majority of mobile devices. the narrower the better since getting them in or out while running is easier if the device is a bit narrower. with the majority of well-designed music devices having the head phones jack at the top, that one is also well accessible, when sitting in the armband. further, the transparent plastic window allows you to use the device, which is useful as long as you carry the armband in your hands, once it’s on the arm, you still could but you don’t want to fiddle around with it one-handed anyway. while running it stays well attached to your e.g. just above the elbow, carrying comfort is ok, but depends on the thickness of your arm. most probably this armband was designed with some good looking californian body builders in mind, because the long backstrap is way oversized for a bony marathon upper arm. i guess some tuning will do the trick, some velcro fastener 
patches at the right places should fix that. regarding moisture, the device is sufficiently protected, a bit - mostly coming from your own sweat - goes through the back of the pouch, but not to extents that one would assume your device sweating with you.
a big bummer is when you need to take the device out while on the run, e.g. to capture a quick snapshot or something else, which is quite common if you use a multimedia computer instead of an iThingy. putting it back in requires too much focus, often to take the armband off and come to a complete standstill. here are some improvements required as well. first, an extension to the back of the pouch, so that it’s easier to slide the device into the pouch and not completely behind it. secondly a hook needs to be attached to the strap that prevents the strap from sliding open completely when using a bit of force.
all in all this thingy is an improvement over carrying the mobilde device in your hands. It could be better with the mentioned improvements and most probably i’ll do them myself. so the verdict:it works.
but, hell no, i won’t take any calls while out there running!
