QUOTE
"The most obvious changes are the new style for the admin screens and the new WYSIWYG post editor. Other changes include a new Role and Permission based user security scheme, built-in object caching, improved image uploading, new options for the default theme, and better abstraction for database access. There are many other changes under the hood, with an assortment of new features and API hooks that plugin developers will be able to take advantage of".
Check it out: www.wordpress.org
and the changelog: http://codex.wordpress.org/WordPress_versions
upgrade is a breeze... good thing i have not made much progress yet with my blog and am still searching for suitable plugins to enhance it. 
