Yes, Playground Sessions is a legitimate online piano learning platform. It has received positive reviews from users and is co-created by music industry legend Quincy Jones. The platform offers a variety of well-known songs to learn in both simplified and authentic versions, and a comprehensive 'Bootcamp' lesson plan. It's recommended for those looking for a good practice tool. However, it's always best to try out the platform and see if it suits individual learning styles and needs.