The author of the article has been running a federated GraphQL implementation for over a year at StockX and has learned several valuable lessons from the experience. They highlight the importance of building the schema incrementally, documenting it thoroughly to make it easily consumable, and experiencing significant performance improvements due to reduced payload sizes. The implementation also revealed a learning curve due to its different API style compared to RESTful APIs, but this was overcome with faster development cycles and a more unified caching strategy. The team had to adapt to using distributed computing best practices and scaling horizontally to serve large traffic loads. Throughout the process, they emphasized the importance of reading and continuing to learn about GraphQL to make informed decisions and improve their implementation. Ultimately, the migration to GraphQL has been a major success, enabling faster development cycles, smaller code deployments with fewer problems, and rethinking their UX.