My 520 just finished updating. I have a developer account so all I had to do was install and run the Preview for Developers app and then check for updates. I have the GoPhone (AT&T) 520, but i flashed a CV ROM on it. The GDR3 update went through just fine. The total time from start to finish was about 20 minutes. It's my 2nd phone so I don't have much on it, making the data migration part short. The most important update for the is the screen rotation lock!