YMMV but the current docs seem fine to me. Though it was pretty bad during the Remix -> RRv7 transition. You can also learn a lot from their github activity (proposals/rfcs/issues). API docs have some additional docs too.

New devs coming in and expecting the framework to be with "batteries included", which it absolutely is not, will also have a bad time. Node apis, ALS/context, handling app version changes on deploys, running the server app itself (if in cluster mode, e.g. with pm2, what that means in terms of a "stateless" app, wiring up all the connnections and pool and events and graceful reloads and whatnot...), hell even basic logging (instead of console.xxx) ... all of that is up to you to handle. But the framework gives you space.

People new to React and/or Node will be confused as hell for quite a bit... in such a cases I would add like 3 months of personal dev time and learning to just wrapping your head around everything... React docs themselves say that you should use a framework if you're using React in 2025 - but it's not that easy. There is a cost, especially if you go the full stack route (client + server + hydration) of having everything under one "typescript roof". The payoff is big, but definitely not immediate.