The idea is worth one Black Mirror episode, but the story lacks... foundation. It's never clear or given a single hint why the app is made, who made the app, or who Xavier is. Everything feels like a middle chunk of a cake without any defining edges. If you're looking for a fun, quick, everything-is-up-to-your-imagination (mind the reference) reading then this could be an option for you. Other than that, it doesn't offer much.