Last Successful Date:
This shows date and time of the last successful run in which files were shadowed.  If you use the /c switch (changes and new files only) then only files from this date onwards will be considered for shadowing.  If there were any warnings or failures during a run then this date will not be updated and the offending files will be re-evaluated at the next run.  You can actually change this date yourself. Useful if you are using the /c switch and want to pick up some older files.