Better than D3 on release, but I doubt it's better than D3 on its latest form.
I miss the matchmaking from D3, and D4, for being an "mmo" of the likes, it doesn't feel very social.
Lots of things that don't work for me, like itemization, build/loot diversity, balance all around...
Other than the art, it doesn't really feel like an upgrade, at least for me.