Well, it's mostly annoying if people store office docs on some samba share instead of in SharePoint/Teams. Also Teams has issues on Firefox, and sometimes also in Chromium. But overall works well enough (even with my AirPods on Linux). Things like drawing in PowerPoint in the Browser have become significantly better over the last year, before that I avoided it like the plaque. Whats missing in MS365 online is numbered captions for figures (unforgivable!), or reference management. That just really annoying if people use those features. Also, I worked in an org still on Office 2019 but mixed it with MS365, that also lead to lot of pain. It's papercuts mostly, nothing fatal.