said by sivran:It's a plus for the average user who doesn't know any better.
It's annoying for more savvy users, for whom unscheduled updates might break things.
+1
I prefer to update most software myself, so if any problems surface it's easier to trace back the cause.
But when I've set up software for friends/family, I always set it to auto-update because I know that they won't think to do it themselves.