You may want to wait until you hear back from me to ensure compatibility. If you have already upgraded to WP 3.8 and are experiencing issues:
You may just need to upgrade your plugins (if updates are available) or deactivate certain plugins that are not shown to be compatible with 3.8 (go to http://wordpress.org/plugins/ to check each plugin's page).
Other possible causes include something happening during the upgrade to the database, permalinks structure, or file permissions for various files (both in WordPress and the theme).
I will add a comment here once we have tested our most popular themes (along with instructions on what to do if the theme you're using isn't listed).