I’ve only been using the new version of Mac OS X for a few hours, but I already like what I see. As others have commented, many of the most satisfying changes are simple clean-ups that should have been done years ago. Like this one:

Notice that the icon for iCal has the actual date, not “Jul 17,” which is what it had since iCal was introduced 5 years ago (on July 17, 2002).