Many of the changes that recently stirred doubts that Blizzard's Diablo III may not make its early 2012 release date window have already been added to the closed beta test. Though the game is still about beating up the bad and getting the treasure it definitely needs another look.
The actual playable content hasn't changed since the closed beta's launch in late 2011. You still smash through an early part of the game then fight the Skeleton King. But there are lots of changes!
Blizzard still appears to be looking into how active skills are swapped in and out. In Diablo III, you'll eventually unlock six slots to assign active skills and three slots for passive skills. These function as your character build and are easily modified, letting adjust your class' strengths on-the-fly. Initially in the beta it was possible to swap out skills as often as you liked, though Blizzard was concerned this ease of switching encouraged you to play with the skill window open at all times. A later version required you to visit an altar in town to switch skills, locking out your ability to change skills in the field. In the current version of the beta, you can again swap skills whenever you like, though swapping triggers a 30 second cooldown during which swapping is blocked.
Many of the changes are still in-development and could be tweaked further before launch, but other things like the removal of Scrolls of Identification and Scrolls of Companion sound permanent, based on what Blizzard's said in official posts.