With all that gray I think the room looks a bit sad. It may be fine as the on-trend color in an adult world, but children respond to strong, vibrant colors.

Montessori schools recommend painting the walls in children's classrooms and private rooms at home in a strong wheat color, a tone that is warm and cozy. Add some natural wood furniture, some painted furniture, and use mostly primary colors with some warm neutrals for most everything else.

The rug looks good for playing with cars!