As you can see, this board is now running a preview version of vBulletin 3.5.
The first thing you'll probably notice is lots of Javascript errors. These are caused by your browser having the old versions of the scripts stored in their cache. Simply hit the refresh button on pages that show an error and the errors should go away.
It's also important that you hit refresh on a showthread.php page before you try to use the quick reply feature, as some of the code behind this has been changed.