As someone who likes haunted house adventures I've played and DM'd a lot of them. The challenge I find in building tension with a group of players who may very well be sitting in a well lit room eating snacks and sporadically looking at their phones is to create a sense that they are surrounded by things that a 'wrong' and unnatural without constantly reorting to combat encounters or saves of some sort. The Haunting Of Heather House does this EXTREMELY well.

Every single room in the house is like a minor character unto itself with an event and something to keep the players on edge and make them feel like they are never safe even for a moment in the house.

The maps of the house are gorgeous and the Tension/Haunting mechanic means that although the start and end of the story will remain the same the journey from beginning to end can be replayed multiple times with surprises still to be had on successive playthroughs.

Even if you are not a Ravenloft fan or not planning to run this adventure I would still highly recommend buying it to cherry pick and insert elements from it into any other haunted settings you intend game as there is some absolutely terrific material to be had in here.