fmsc88
No issue at the moment. Only a problem with lightbox in attachments posts, if you are using db attachments store, and CDN configuration in config.php. ( attachments are opened in new browser tab, and not in lightbox. In XFMG no problems.)
For what I see in official XF forum, will be solved with 2.2.1 realease.
Of course you have to check if you are using some addons not certified with 2.2 version.