nice votes so far, pvp leading

I hope that diablo 3 will have epic monsters and bosses

So do I...

the duels no doubt ;) and i look forward to the new classes and items :D

duels? Great and 1 billion times better than ladder slasher
New classes and items? Looking forward to that too

actually everything^^ but mostly pvp

The most important parts for me would have to be the feeling of the game. Specifically...
Mfing - things like meph runs and you finally get a badass item, i always got a rush from that
Items - again, finding good items feels awesome, i like the unique/rare item system in d2 but they should actually be switched... how can an soj be unique if there are millions of them lol
Pvp - fast paced, fun, and simple. i always had a rush pvping

the second to last one