We use Azure DevOps for a fairly large project and so far its working good (i.e., not great, but better than okay-ish). The point with the lost communication is something we also experienced more often than I would wish for, however, on a standard day I do not see the issue appearing at all.

Yes, the mobile page could be optimized (but this is not a deal breaker) and yes some pages do not subscribe for notifications, but usually all these things are not in the hot path.

TL;DR: Lots of improvements in the recent year and many things to come - it may not be perfect but it certainly is usable and provides value to our team.