Read the release-notes. Check if your (most used) functions and programmes warns about "functionality will be removed" when you run them, make sure to set:
warning('on','verbose')
% possibly also
warning('on','backtrace')
That might catch some features you might have to update for.
Install the new version and see if it works OK while keeping the old one as a fall-back option. If there are problems just uninstall the new one?
