I had one of these bags until a couple of hours ago, when it decided to make use of the 'quick' part of the 'quick release mounting' and disappear somewhere throughout a 30 mile ride. 
What pisses me off most is that it's sold as a small bag to keep essentials like a mobile phone or wallet - both of which I am now down! Some lucky wee scrote somewhere is laughing that they've managed to get hold of an iPhone (it went straight to voicemail, meaning it was switched off by hand) and my cash, while I'm left cashless, phoneless, and starving.
The main failing of the product,in hindsight, is that it only attaches to the saddle rails on the QR mount - perhaps a velcro strap around the saddle would have been an idea?
