Early on, I thought, "This book reminds me a little of Mercy Watson." And then I remembered that Kate DiCamillo wrote Mercy Watson. The characters are beyond quirky, and the vocabulary is high. This makes it appealing and fun for many adult readers, but I suspect will work for fewer young readers, and probably for nobody under 4th grade. 
 I enjoyed the cartoon panels added throughout - they really helped me visualize certain scenes - and the way that adults were portrayed as all kinds of weirdness, good and bad, thought I remained a little worried about the dad throughout. 
 My favorite line (about marriage): "Such tenderness. To have someone get out of bed and bring you little fishes and sit with you as you eat them in the dark of night. To hum to you. This is love." 
 And this is probably the only time I'll ever tear up at a poem written by a squirrel. Sheesh.