One of the design choices which again shows Blizzard Irvine's hand in the changes made is the re-appearance of the Barbarian character class -- the original design documents for Diablo III included a set of all new character classes, with no reappearance of old character classes (our reasons for this was simple -- since we were enhancing and improving the skill system, we didn't want to try and adapt old skills into a new system -- we'd rather create all new skills for the new character classes. The return of the Barbarian class feels like a change that was made after development of the title was moved to Irvine 3 years ago.
One of the reasons why the Barbarian return shocks me so much is that I always felt that the Barbarian character class was the most broken of the classes in Diablo II. The Barbarian's ability to Leap, for instance gave him advantage over other classes which had to walk around the barrier -- it is the showcasing of this skill in the video (during which a bridge crumbles away, leaving no way to cross the gap) which makes me wonder if they have an alternate way for other characters to cross the gap or if all the characters have Leap now.
Of course, going 3D means that a lot of the things that were hard to do with sprites (such as actual armor looks being reflected on the character) is much easier using polygons and textures, as well as real 3d lighting. The use of a physics engine (Havoc, according to the game specs) is also a nice touch.
While I have more or less given up on the PC as a gaming platform, I'm glad to see that Blizzard is still committed to releasing titles that aren't first-person shooters; such a shame that we won't be seeing this title on the shelves for another year or two at the earliest.