My beef with vacuum systems is the greater likelihood that a single failure will take down the system. As Larry mentioned, this is possible on late model cars with an ECU for the door locks. Our 97 Caravan is susceptible to this but the first 125K miles have been trouble free in this regard. To Eric's point, I've seen more MBs with vacuum lock problems than the aggregate of cars I've seen with electric lock problems. But that's just another unsubstanciated statistic.
Eric, are you really concerned that miscreants will pour something into the fuel filler when the rest of the car is unlocked? Most American cars don't have locking fillers.