I've been running testing/trixie since the end of 2023 or so. (I generally always run testing, but stick with stable for ~6 months after stabilization, in order to avoid lots of package churn in new-testing.)

It's been what I expect from Debian: boring and functional. I've never run into an issue where the system wouldn't boot after an update (I usually update once every 2-4 weeks when on testing), and for the most part everything has worked without the need to fix broken packages or utter magic apt incantations.

Debian has always been very impressive to me. They're certainly not perfect, but what they can do based on volunteers, donations, and sponsors, is amazing.