This release comes with a new syntax quide, an improved faceted search and the ability to import content from Confluence wiki. Also, the wiki creation wizard has now support for creating wiki templates and for choosing the user scope (local, global or both). This release also includes a lot of bug fixes (33) and a few improvements (19) so you should definitely check it out.
Full release notes available at http://www.xwiki.org/xwiki/bin/view/ReleaseNotes/ReleaseNotesXWiki53M2
See http://jira.xwiki.org/secure/IssueNavigator.jspa?reset=true&jqlQuery=category+in+%28%22Top+Level+Projects%22%29+and+fixVersion+in+%28%22%35.%33-milestone-%32%22%29+and+resolution+in+%28%22Fixed%22%29 for more details