Diablo 2 USED to be really cool, until they unbalanced it with patch 1.10. After that the game simply wasn't the same anymore, only the "cookie cutter" builds would really work and if you want to survive the hell difficulty you need uber gear, which you will not find so quickly.
Still, even with patch 1.10 I had a lot of fun playing it, until Guild Wars hit the market
What worries me with D3 is the gameplay video.
It's... too common :/
well it is an early gameplay video, that was clearly hacked for show and tell purposes. I do not think that mana will regenerate so quickly in the real game, nor that enemies will fall so easily. Otherwise why would you need a team if you can swat hundreds of enemies that easily with only one barbarian?
I really like the way you can use the environment as a trap, I miss that in most RPGs, especially online ones.