I had installed WordPress 2.7 as a beta last month.  When the final release came out WordPress notified me, but instead of like previous versions, it just let me click a link and it handled the upgrade on the server with very little fuss.  It was like buying a 2008 Honda knowing that when the 2009 Hondas came out you could push a button and for free your Honda would upgrade to the latest.  Before several steps were required, now, I just click a button.  Wow.

The new interface for administration is very clean and polished and easy to use.  Wow.

The ease of editing posts has been taken up just a notch, which is quite nice.  Wow.

I can install plugins from within the plugin interface without having to download and unzip zip files, it just works.  WOW!

Thanks to Matt and the rest of the team at Automattic for a fantastic release that is well worth the upgrade.