Recorded by someone up nice and close to the stage at Gamescom 2013, you can watch the entirety of Blizzard's Diablo 3 presentation on YouTube. This is not an official Blizzard video, so there's a chance it'll be taken down (although this isn't an official Blizzard event either, so who knows -- either way watch I'd watch it soon).
One of the big things that stood out for me was when they were talking about the end-game; Blizzard wants there to be something for everyone in the end-game of Diablo 3, not just for the hard core players. This feels like a departure, somewhat, from previous paradigms; and is certainly an echo of what WoW's end-game has become.
You can watch the trailer for Diablo 3: Reaper of Souls over yonder, and also read up about what we heard will be coming in a pre-expansion patch to Diablo 3.