Australian Shepherds are very intelligent and devoted to their family. They can be very good with children, but one should always exercise caution as with any animal and a child.
Children:
You will need to teach the child to respect the dog, and the dog to respect the child.
Dogs tend to see children as siblings rather than leaders, and the dog should never be allowed a higher position than the child. The parent, not the child, should be responsible for teaching the puppy and correcting the dog if it gets too rough.
Other Animals:
Aussies, if properly socialised, can get along with any kind of animal.
However, as with any dog, an Aussie must be properly introduced to different animal species (including other dogs) in a favourable environment otherwise, problems with species compatibility may arise.