We've had an awful experience with Next. There are undocumented, broken things all over the place. Migrating to the App Router was a huge mistake. 'use client' didn't work as expected, and we had to install workarounds and try out different hacks to get access to the most pedestrian features we could expect from any other web framework.
This is the broad consensus among everyone else I know using Next - they felt like the Next 13 release and the app router was a rug pull from a previously pleasant experience.
And whenever you complain about this or ask for support, some devrel guy from Vercel shows up in your replies, saying something to the effect of "Wow! That's crazy, we worked really hard on Next 13! This is my first time hearing about this!"
Edit: Since I know the devrel guys are in this thread: If you want people to keep using Next, something fundamental about how you guys write the framework needs to change. The instability and lack of documentation makes developing with your framework a massive pain in the ass - anyone I know who can is migrating off it as quickly as possible.