I get the following error on install with a brand new WP 3.5 setup with no added themes or plugins, Received the same error on a different WP 3.5 setup. Also, after install there are errors on each configuration tab.
"The plugin generated 12482 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin."
or "Warning: Missing argument 2 for wpdb::prepare(), called in C:\xampp\htdocs\testsite\wp-content\plugins\the-online-booking-system\employees.php on line 2296 and defined in C:\xampp\htdocs\testsite\wp-includes\wp-db.php on line 990"
Would consider buying the full version with no errors :-)