Main changes are:
The way that the 'Run Program' and 'Run VBScript' modules start their tasks.
Specifically: if task cannot be started using the 'Local System' login (because for example it requires UI access) then the account of the currently logged in user is used.
The Web Service module was modified to be better handle more complex responses.
Some of the Result Variables created by the "Call Web Service" module have changed as part of this modification.
Other changes are private custom extensions made for specific users. These are not publicly documented.
If your system does not require additional features then would recommend continuing to use your current setup as-is.