All I'm interested in is music and characters. I don't want everything ruined.
While I would love to see some bosses, I would rather be left in the dark and accidentally stumble upon one during game play. I remember in Cloud Cuckooland I ended up going into Mingy Jongo's skull first without even knowing there was a second skull in the level. The surprise was perfect. So, no bosses, please.
I'm also fine with no more world reveals, either. I love how much we're speculating about the swamp/haunted levels, and the speculating is what makes it fun. We don't know if we're right or wrong. Would much rather be left in the dark.
What I've noticed in the gameplay footage was that there was little music, which is why I'm interested in hearing what they've assembled for the levels/areas we've seen thus far. The trailer music is great, but I'd like a matching up of music/area.
I also would like some more npc reveals. Or even better, more mumbling revealed without a character attached. Wouldn't that be fun to try and guess what kind of character it is by their mumbling?