I want to be scared in the expansion. I want to see something sinister, I don't want a 30 second cutscene, I want to walk into a room and get crushed. Diablo 3 could learn something from its predecessors and games like Dark Soul. You should fear walking into Duriel's Cavern because he's not waiting for you for you to ready yourself, and definitely doesn't have time to talk. He's ready to crush you. In fact, you should always be timid to be the first person to enter that hole.
I want to feel fear in a Diablo game again --- and part of fear is self-manifested. In Diablo 2, I don't know much of anything about the story except for the particular quests building up to bosses. The minute Diablo appears after a rumbling cathedral with "Not even death can save you from me", I literally almost !@#$ myself as this giant demon sprinted towards me to kick my %^-, rather than talk about his feelings.
Similarly, I'd like to see some grid map randomization, they leave room for more randomization--- I recognize every environment far too easily and can anticipate where to go, where things are, etc.
Anyone else feel free to add your thoughts to this thread