The review on Wired.com is that it is useless against hardcore city bike thieves... but just about everything is, to anyone with a car and tools, about nothing is theft proof... high speed rotary cutoff wheels will slice through Kryptonite and all the other stuff you think keep your bike chain and locks imperivous.
http://www.wired.com/gadgetlab/2011/10/bike-bottle-lock-trades-security-for-convenience/