We have a Sheltie and taking care of the coat is important as with any dog with a long coat. We live in an area where temperatures can reach 110 degrees in the summer so we her hair short when it heats up.
They love to run, they are sheepdogs after all and need some space to do so. A large yard or regular access to a park is important.
Shelties, or at least ours, love attention. They always want to be around us and love to be petted. This is not a problem for my wife but to be totally honest it gets a little annoying for me. Over all, they are great pets and do really well with our children.