".a satisfying, well-plotted picture book." Booklist, ALA, Starred Review "Waber has given an original twist to the familiar theme of the test of friendship." Kirkus Reviews "An entertaining and subtly edifying portrait of a robust friendship." Publishers Weekly "The book gets to the heart of what is important to children, and the color illustrations are vintage Waber with great facial expressions and humorous, child-friendly images." School Library Journal "Waber's characters, loosely sketched hippopotami, show their emotions freely, allowing young children to laugh with them without forcing an obvious lesson through mirror images of themselves." Horn Book.