GameInformer: "Make no mistake: This is a game for young players and their families. Only the most die-hard Achievement hoarders will have the endurance to stick through it if they didn’t start off with a love for Sesame Street and its characters. If you’re under the game’s intended umbrella, however, it’s one of the best family focused games ever made.
If you had to distill Once Upon A Monster to its essence, it’s a series of educational minigames that you play with Kinect-based motions. Reducing it that way would be a mistake, however. Double Fine absolutely nailed what makes Sesame Street what it is, from the Muppets’ loveable personalities to how educational content is cleverly masked beneath storylines that kids can relate to. It’s all strung together in a series of vignettes that make up larger chapters in the game’s virtual storybook."