I running the 10080 build on my L920 since the day it was released and liking it a lot. Below are the bugs that i am facing:
1. Unable to ping the apps that was previously pinned to my start screen when i was on wp8.1.
2. Unable to download additional phone languages and speech and as a result cortana is not working.
3. Many apps that i have installed does not seem to work (but these apps are not so frequently used so i am ok with it).
4. Calendar preview crashes when i try to open recurring appointments and also does not update the upcoming appointments on the live tile. But i do get appointment alerts in the notification center.
5. Outlook preview does not update the live tile either (but no crashes). No notifications for new emails in the notification center and on live tile.
6. Start screen very rarely goes to loading... for a few seconds.
7. Photos app does not show the albums.
8. Caller ID feature does not work at time (does not show the name of the person calling, though the contact is saved in my contact list).
9. Battery Saver does not work. So you cannot block the apps from running in he background.
10. Glance screen has disappeared.
Other than these, my phone works pretty well. I get the same battery life i used to on wp8.1 and the phone also does not heat up. All of the above bugs have been reported to MS via the feedback app. Hopefully they will fix them in their next build. Loving the new Outlook, Calender and Office preview apps.
For those who have issues downloading additional keybaords. Try this:
1. Install the Windows Insider app (if you have uninstalled it... I had :smile
.
2. Open it and repeat the process of getting new the new Windows 10 build.
3. Now download add the additional keyboard and check for updates.
This is how i installed additional keyboards.