In reality, this may be of very limited use only. Check the following thread:
http://www.thebeijinger.com/forum/20...ly-meaningless
While the last entry was over a year ago, I believe nothing has really changed on this. Anybody wanting to try this gambit out should first contact the local office of a car rental company in the Chinese city you want to drive in. Also check if there is a provisional license for that jurisdiction, since these licenses seem to very location-restricted.
Clearly, this device was not meant for tourists who want to use the car for any sort of intercity driving or extended trips. It is not a substitute for a regular, "permanent" Chinese license.