Good overview. One thing that's shifted since a lot of these explainers were written: Next 15 flipped fetch and GET route handlers to uncached by default, so the automatic caching selling point now needs an explicit opt-in with cache options or the use cache directive. Also worth caveating the ISR description, the very first request after a deploy or a cache eviction still pays a full server render, the CDN only has something stale to serve once at least one request has populated it.