1. Your Joomla is now even more secured
From this version onward, the minimum PHP requirement has been raised to PHP 5.3.10, which has fixed a number of critical vulnerabilities from the older PHP versions. Joomla security is definitely tighter and strengthen with this change.
2. SEO friendlier with microdata
A new microdata library is shipped with Joomla 3.3. The microdata will allow you to identify the article’s author, add on microdata info to breadcrumb links, get the rich snippets to bring forth your content for reviews, ratings, etc. This will certainly empower your content to be favored by search engines.
3. Hello to Cloud Storage APIs
Cloud storage APIs are now being integrated for use by developers to provide support for popular cloud storage providers such as Amazon S3, Google Cloud Storage, Rackspace and Dropbox.
4. Front-end module editing now possible
You can access and edit modules right from the frontend. Collaboration on content now is much easier without the hassles of digging into the back-end.
5. Less code conflicts
It's official that Joomla 3.3 core onward will be JQuery only. It now has its own JQuery library. Mootools code instances have also been converted to use JQuery as well. As this is implemented, Joomla extension developers can all use one single JQuery library, reducing the conflicts among those extensions’ JQuery libraries created from each extension developer.
Until then, stay calm and get yourself ready for Joomla 3.3!