I have a three year old and he is completely obsessed with the original Happy Action Theatre. He's been counting down the days till this one and it didn't disappoint. And I'm honestly having a great time playing it with him. Some of the games are really simple but they are enhanced by the cool video game nods and references, like when you're suddenly wearing a Minecraft costume (a game he loves to watch me play) or a costume from Costume Quest.
I'm almost sad I got it free. They deserve to get paid for something so cool. Highly recommend you get it if you've got a Kinect and a kid.
Plus, he's earned me almost all the achievement points already :-D