I'm still seeing problems. I've had several cases where after the upgrade, a subsequent program update stalled, disabling the antivirus.
Removal and resinstalation fixed all except one - which is a Win7 machine which has always shown weird behaviour with file permissions when installing Avast
Two minor issues with it - if you've overridden the default scan action options, then not all of these are carried through after the upgrade. You need to check each scan type individually
And some older programs - notably MS Office 97 and 2000 - are not in the database of whitelisted applications. By default it tries to open them in the sandbox