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Of course, this won't help much if you've messed with the code (like I always do), but at least you don't have to go through the process of manually updating your blog every time a new version is out, which intimidates many users.
Other important changes are speed (WordPress should now be all-around faster) and the ability to customize every screen. If you never use a certain option, you can now click on "Screen Options" and remove it, move it around, or turn it into an icon if your screen estate is limited.
For an introduction to new WordPress features check out the video below, and you can download the new version here.