David James shares his experience of rebuilding his portfolio website using GatsbyJS, highlighting the benefits of using this React-based static site generator over traditional WordPress themes. Inspired by Scott Tolinski's video, James chose GatsbyJS for its ability to create fast, modern sites with blogging capabilities and the flexibility to integrate with APIs or CMSs like WordPress. He describes how easy it was to use Gatsby's GraphQL features to query data, simplifying the process of pulling content from WordPress and enhancing his skills in React and JavaScript. James emphasizes Gatsby's impressive out-of-the-box performance, achieving high scores on Google's Lighthouse tool, and expresses his intention to continue using it for client projects due to its efficiency and the growing demand for performant websites and Progressive Web Apps.