I got 2.4 today.
Its looked bad..new EUA and it now Needs mic and camera access.
It looked like all settings in GC were lost. The GUI after install inferred it did not have any devices in its list. The watch paired instantly but 2.4 kept telling me nothing was found in the BT search.
When I tried to back arrow out of the app there were my two existing device profiles.
Looks like my user data is still available but I did have to turn back on my custom HR zones.