NEXT.JS APP ROUTER MIGRATION: THE GOOD, BAD, AND UGLY

Summary from the TLDR Web Dev newsletter

The Next.js App Router allows for better flexibility of layouts, loading states, and initial data loading on the server. However, it has drawbacks such as the need to add client-side fetching for live UI updates, server-side errors being easily hidden, the inability to implement route exit animations, and issues with routing type safety. The Next.js App Router may not be fully production-ready yet as it still has memory leaks and lower dev server performance.