We have used esbuild for the last 8 months. It’s wonderful. Means we can have a simple “watch” and rebuild the entire project every time something changes. No need for complicated incremental build pipelines.
I like esbuild a lot. It’s easy to use, basically doesn’t require any configuration. It’s fast. I use it on TypeScript/React/JSX projects. The only tricky-ish part was figuring out how to get it working with Jest for unit tests. https://github.com/aelbore/esbuild-jest solved that just as easily too.
I have been trying esbuild at work to see whether we can replace our old browserify and webpack builds. The results have been very promising with a single esbuild dependency replacing a multitude of webpack loaders and other dev dependencies. The build times were also much much faster.
The only two downsides that prevent us from migrating to esbuild are ES5 support (we need it for one project) and code splitting (we use dynamic import statements to fetch customer specific configuration).