This book is an upper elementary or middle school fantasy. It is age appropriate with nothing objectionable in it. It is a story of sibling rivalry and mysterious magic.
Howard's family is headed by an ineffectual father, Quentin, an author. It is led by a strong mother, Catriona, a music teacher. The story focuses more on Howard, the older son, and Awful, the younger daughter. They are forced to deal with a family of very immature wizards who seem locked to their community.
The story is cute and it should keep the interest of the appropriate age group.