There seems to have been a few common issues on initial release which have been patched up already. The following files have been changed:
If you want, you can just extract the above files and overwrite on server. Keep in mind, you may need to make a small change on any page in your content, because this is how X3 knows that it is to purge certain cached PHP scripts, and re-create PHP template files.
.htaccess default.htaccess app/cache.inc.php extensions/twig.imagevue.inc.php i.php
* i.php has been added for diagnostics.