Make sure that if you use this beta, you also update to the final 4.5.0 version when it is released.
Textpattern 4.5.0 renders your sites in modern HTML5 or yesteryears XHTML at your discretion, has a beautiful new default template with lots of state-of-the art front-end goodies baked right in, ships with Textile 2.4, can import current WordPress sites flawlessly, and admittedly fixes a few bugs.
On the technical side we have upped the minimum system requirements to PHP 5.2 and upgraded the bundled jQuery to version 1.7.2.
Post your feedback in the forum thread or in the comments below.
Do not use this beta release on a production site unless you have a working backup of both the site’s files and its database and know how to use it.