Yeah .. they're really useful
Downside is that if you access someone else's, with their permission of course, you need to be able to get hold of their authenticator.
Unfortunately this means I am unable to log onto my fiance's toons if I needed something he had. Being that there's a 7hrs time difference and several thousand miles of ocean between us I just can't quite reach his authenticator - rofl.
Just as well they made me an officer too, one less thing I would have not been able to do as he's an officer too.