I don't have much experience w/ Dobermans personally, but do know that males have a tendency to be same-sex aggressive - big time. Responsible breeders will not place a male Dobe in a house with another male unless you are a very experienced Doberman owner and willing to crate/rotate if necessary. They may be fine for the first 3 years of their life and suddenly develop it, so just something to look out for.
Unfortunately, one of my aunt's husband's siblings just had her Yorkie killed by a Doberman who ran across the street and viciously attacked her.
It was apparantly a horrific site. Sorry to relay negativity, I wish I had more experience w/ them, but I don't
But they seem like such cool dogs - so regal looking. They do have a lot of health issues and often live a relatively short life.
Jackson has spent lots of time around my uncles German Shepherd female, who is now around 8 months... they very rarely play, he just prefers to not even get her started because he knows she's so much bigger, and her play style is a lot rougher. He also grew up around a Rottweiler pup and they got along GREAT - both very much respected each other. Jackson helped raise him.