I manually updated to Android Wear 2.8 from 2.7 on my Zenwatch 3 but I did not and do not see any differences at all.
If anyone wants to manually update to Android Wear 2.8 here is the download link for the Android Wear 2.7 APK which enables the 2.8 update to appear on your your phone's playstore and your watch's playstore.
First install the 2.7 android wear apk into your phone from the link below then wait 2-3 minutes and go to the phone's playstore and check for updates, you will see the android wear 2.8 update for your phone.
After updating the phone to the 2.8 update wait 2-3 minutes and the 2.8 update will also appear in your watch's playstore after you check for new updates in the watch.
The Android Wear 2.8 update is not device dependant and it can be used with most any android wear watch which has the Android Wear 2.0 firmware in it.
Here is the download link for the Android Wear 2.7 apk which allows the 2.8 update to appear in both your phone and your watch.
Good luck, have a great day!
from XDA-Developers - Latest Comments by Misterjunky