I still can't believe they're making another Luigi's Mansion game. I mean, I see this trailer, and some part of me acknowledges it, but other parts just laugh and say "right, Luke, and next thing you know they'll make another Pikmin game..."
Personally, I found the original Luigi's Mansion legitimately terrifying. I may have been a kid at the time, but I don't think that's the only reason I believe that. It not only knew how to set an atmosphere, but it wasn't trying to push that dark and grim atmosphere in your face every second like Dead Space or modern "horror" in general. There were moments where it was creepy and moments where it was comical and moments where it was both; there didn't have to be gratuitous blood or gore to be scary, and the horror stories (i.e. most of the portrait ghosts' backstories) were subtle and implicit, sometimes even making you feel guilty for vacuuming them up. And let's not forget the blackout; no one can tell me they weren't at least chilled during that descent to the breaker room.
I can't say anything for certain, because the trailers so far all seem to use music where Luigi's Mansion was at its best when there was none, but the environmental art style seems more cartoony and the lighting scheme brighter, but I don't think this game is going to have that same atmosphere, unfortunately.