Lotta changes sound really good. D3 fixed the one huge thing that's always bugged me about loot-based ARPGs like Borderlands and the like. In a game where you're basically doing the same thing for hundreds of hours, the core combat loop better make me want to do it for that long, and D3 had that. The moment-to-moment gameplay feels better than anything in D2, PoE, TL2, anything else you wanna name.
But the loot was ass, and the economy was ass, and the rare/legendaries often were just junk, and the difficulty balance was out of whack. But it does seem they're fixing a lot of that, or have since launch.
I also really like the idea of ladders, just everybody starting on the same foot and kinda competing with each other(even though its really about who puts the most time in the game not skill but whatever). And Loot runs!