Temperament...

Well-bred GSDs have powerful jaws and strong teeth, can develop a strong sense of loyalty and obedience, and can be trained to attack and release on command. Poorly bred GSDs such as those from puppy mills can be fearful, overly aggressive, or both.

Dangerous?

GSDs (like Pit Bulls, Rottweilers and Dobermanns), are often perceived as inherently dangerous, and are the target of Breed Specific Legislation in several countries.

If a GSD is violent or aggressive, it is often due to the combination of poor breeding (bad nerves) and the owner's lack of control or training. GSDs are often used as guard, attack and police dogs, which further contributes to the perception of being a dangerous breed. However, many GSDs function perfectly well as search dogs and family pets, roles where aggressive behavior is unsuitable.

Loyalty

GSDs' sense of loyalty and emotional bond with their owners is almost impossible to overstate. Separation trauma is one reason they are now used less often in guide dog roles, since guide dogs are typically trained from puppyhood by one owner prior to final placement with their employer.

GSDs can make loyal and obedient pets.

Temperament differences among lines

The different types or lines of GSD display differences not only in appearance but also in ability and temperament.

Dogs from working lines have very high energy, and have been bred to have a natural drive for protection, tracking, and obedience. They are bred primarily for consistent temperament, working drive, and intelligence. These dogs can be used as pets, but will be unhappy if not exercised daily or trained to do a job of some sort.

Many of these dogs populate dog pounds in North America due to their destructive tendencies when not properly trained.

German and Eastern European lines tend to be stockier, with shorter snouts and more muscular chests, and typify the working lines.

North American lines have a tendency towards a longer croup, longer back, higher wither and temperament ideal for companionship. They do not require constant stimulation to keep them from becoming bored and possibly demonstrating destructive behaviors.

These dogs can make excellent pets, provided that a responsible breeder has not sacrificed consistent temperament or health in the quest for popular standards for good looks.

Intelligence

GSHs are highly intelligent and learn new commands very quickly. A study placed German Shepherds as the 3rd most intelligent breed of dogs. This study used a survey of dog trainers who were asked which breeds responded most often to commands and which breeds learned new commands fastest. GSDs placed only behind Border Collies and Poodles.