Ive used it for the past year and quite like it, but there is a steep learning curve. Some thoughts based on the Manifold codebase:

• You will likely need to change some patterns of how you do things at the top of the app structure, but other than that most things can be done incrementally.

• I found it easier in larger codebases to put 'use client' at the top of just about everything while getting started since its not worth also refactoring a bunch of things just to get started while reusing components between pages/app router. You can then refactor over time to do things on the server more.

• The way you are currently using Supabase Admin for server-side data fetching will map easily to the new app router, no major changes there.

• You may need to map the auth slightly differently to make it work but you have a cookie to pass around so should be pretty straight forward.

• Suspense is a really great pattern if you lean into it. Same with nested layouts.

• You sometimes need workarounds in edge cases for the 3rd party libraries that don't support it yet. However over time this will flip and most things will be built for the new app router and not for pages.