Woow. This looks amazing. However "possible" pro and cons are as follows:

Pro:

• Would reduce high risk of accident from drunk fellows.

• Guess who's bank account just shook? The uber driver.

• Reduce high intake of alchol so user drives home himself.

Cons:

• Prone to misplacing due to size.

That notwithstanding, it looks like a pretty cool innovation.

P.S: Possible pros and cons cause i have not used this, so they are just speculation.