A Doberman was the first dog I ever had.
That part about the brain growing too much for their skull is an urban legend.
They rank as one of the smartest dogs. We were afraid that ours would become mean, so we socialized the hell out of it. In fact, we did too much to ensure it wouldn't turn out mean - and it was the suckiest dog in town, not at all a tough dog, not whatsoever.
Talking to other people who keep Dobermans, this seems to be the general rule. Most are pushovers, and very sucky - but socialization seems to be important with the breed.
I'd put them on my list of top 5 dog breeds to own.