Yan's cartoons have the look of modern animation; rendered in bright blended colors, they are sure to elicit giggles with their portrayals of Daisy's failed attempts to engage her grandfather. . . . Comical and heartwarming, this title should spark discussions of relationships and understanding.

– Kirkus Reviews

This precious story celebrates how love can transcend both generations and cultures. The language barrier with a foreign relative is expertly and affectionately portrayed, and both the story and its illustrations are fluidly multicultural. . . . Yan's delightful artwork has all the humor and detail and sunlight of a Pixar film. Many children will certainly relate to this sweet child with a big heart who just wants to make her elder happy-and does.

– Booklist

Pig-tailed Daisy and bushy-browed Yeh-Yeh's memorable expressions illuminate every page, and Daisy's sassy kitty and enchanting wardrobe (unicorn horn headband, fluffy boas and sparkling tiaras she shares with Yeh-Yeh) make for picture perfect scenarios. . . . With Yan's Pixar-ready illustrations and Moore's sweet text about familial communication, Grandpa Grumps invites smiles all around.

– Shelf Awareness

Moore has written a story that many immigrant parents, grandchildren and their visiting grandpas from native countries can identify with. . . . Yan's illustrations capture the mood of every occasion, from the grouchy gray of Grandpa's beard and attire to the confetti warmth of fried rice. . . . Moore invites the reader to learn vocabulary and follow along in Cantonese. It's whimsical and Chinglish, meant to be fun. Fans of Minh Lê and Dan Santat's book Drawn Together will enjoy this story of Daisy's incessant efforts to connect with a Grandpa who seems so distant. . . . This book will tug at your heartstrings.

– International Examiner