User stats work fine in 6.5.1 - albeit you will have to alter the path for main.inc.php to
// Require the library
require ("./includes/main.inc.php");
Admin stats are not working - but this maybe my server (as per my post above (can't recall if admin stats ever worked for me)) and not a problem with the code.
Also on the admin side - the menu system has altered so the menu changes need to be in admin_adminmenu.tmpl.