EDIT 2: Despite the Author's efforts to make things right, the latest version .4 is stuck on migrating and no way to circumvent or skip the process. Can not continue or make it work. It was great while it lasted.
After upgrade to version 7, the previous page counts did not migrate. The migration process ran on first install, but when the status page appeared, all counts were zero.
The plug-in uses new short codes as well. Old ones no longer work. I have at least 20 short codes set up on a statistics page I use for tracking. Not only have I lost my counts, but none of the short codes work.
Just beware - record your counts and be prepared to have to redo your short codes.
EDIT/Follow-Up: I give the author full credit is trying to resolve this issue. In the end, I had to recreate my short codes to get them working again. That said, since the migration failed on my site, I tried to delete all data to start anew, but the global site visit counts will not zero out (it stays above 900).