Yes, Harry is well aware of his limitations, but not of his potential, River Shoulders is a good teacher for Harry, because he will learn from Harry a lot of the human things he needs to be a proper father to his part human son. It’s very much a Michael/Harry relationship.
Aside from shapehifting, River can help him in other areas of his magic, such a negating or deflecting spells, which Harry is starting to use himself, and improving his veils and illusions.