I have upgraded, did you?
Some of the new features including native tag support, plugin update notification, better URI handling that helps your search engine optimization (SEO), advance WYSIWYG editor and a lot more.Some of your plugin might not work correctly as mention at the development blog. Be sure to check that out first and don’t forget to backup your current wordpress installation just in case. You will also need to modify your existing theme to add the tag support. Haven’t done mine yet, quite busy right now.