Txt, WhatsApp, email, calls, calendar and from some selected apps are accurate. Syncing alarms set on the phone is unreliable.
Edit. To be clear, not just a notification. The messages are displayed and can be replied to from the watch if necessary.
Google apparently cocked this up, it was Wear OS v2.21 that was pushed to the Playstore. Also, the Google app updated last week which broke the setting of a timer or an alarm with Assistant on the watch. The voice command is recognized but is not acted upon.
Yesterday I updated to Wear OS 2.3. Google Assistant now works properly but I suppose we now need an update to the Google app update to fix the timer issue. I won't hold my breath for syncing alarms between the watch and phone ever to work.
Still loving the watch but it shouldn't be this much hassle.
After several updates last week the watch has ended up with less functionality than when I bought it 3 months ago. I can no longer set a timer or alarm via the assistant. Did a factory reset and reinstall, still the same.