i think that in certain places, and for use by certain people, driverless cars will be good.
while the best way to have the cars is everyone using them (becasue that way, you dont have human versus machine, becasue human allways fails, becasue we are fleshy, and can forget to sleep or get distracted) we would probably have a percentage using them and another percentage not.
the best people to get using them are, inner city users (short trips type) drinkers (no drunk driving) taxi (no more being driven the wrong way to the destination, so the driver can charge extra. no more going round corners on 2 wheels so the driver can get there faster to get to their next fare) older people (human frailtes and bad eyesight coupled with aged brains just not working like they used to) rentals for non drivers and for those too young to be allowed to drive themselves.
everyone else would, and probably should, continue as normal.
my only real worries have allready been mentioned by everyone allready, except if i had a google driverless car like those little ones, i would want a humanoid shape inthe front/ hell i will even be satisfied with an inflateable JonnyCab style dude, so long as me swearing at him wont make him explode on me lol