You cannot use the EMC to retrieve public folder statistics.
This example returns the statistics for the public folder Marketing with a piped command to format the list.
Get-PublicFolderStatistics -Identity \Marketing | fl
The value for the Identity parameter must include the path. For example, if the public folder Marketing existed under the parent folder Business, you would provide the following value: \Business\Marketing
Using the following commands and comparing to Exchange 2003/2007 you can make sure that each of the folders are replicated fully.
Of all the migration tasks in Exchange, Public Folders take the most amount of time!