After running React 19 in production for a few months, here are my honest thoughts:
Server components are the real deal. The performance wins are significant. We cut our JS bundle by ~40% on key pages. The mental model takes getting used to, but once it clicks, you wonder how you lived without it.
The use hook simplifies data fetching patterns considerably. No more useEffect + useState dance for async data. But be careful with error boundaries, you need them.
Actions are underrated. Form handling with useActionState is clean and progressive-enhancement-friendly. It's the right abstraction for most form scenarios.
The ecosystem is still catching up, but the direction is right. React is becoming a better framework while staying a great library.