Additional "characters" to "say" things

[Rohful]

One thing that's a little strange about the mansions - there's never anyone there except for critters trying to attack you. Now... maybe the critters already drove off all the people. Still, it would be kind of nice for at least some non-deserted parts of mansions, even if the interaction is very basic.

I think MM has always been about this 'nostalgic' feeling of exploring rooms and solving puzzles.

Some animated sprites here and there perhaps either giving you a hint on how to solve the mansion or some background information would be a nice way to keep the game 'fresh' and interesting, I agree. Though I think the ability of making inanimate objects interactive is still a nice touch.

Also, I think there should be something to show Jack's thoughts if you understand what I mean.

What about those little animations when you leave Jack idle?
I think it's a nice way of showing his feelings... unless you mean there should be some way of expressing this in more detail?