The D&D 5e book Van Richten's Guide to Ravenloft includes an adventure called House of Lament. Last year, I ran House of Lament for a group of players, and later that year I played in House of Lament with a different group of players. This is my review of the module as a player.
Before I begin my review, though, I want to clarify that yes, I was the Game Master for the module before I was a player in it. This isn't the conflict of interest it might at first seem to be. For more information on how this works, read my post about how to replay modules honestly.
The idea of having a host character in the house for the duration of the adventure turns out to be awkward. I don't care what character you choose to be in the parlour, it's just weird to have an ally in the house that you're exploring, who just won't ever leave the parlour. The Game Master can obviously play the character to do anything, but then you've got an NPC driving the narrative and that's no fun for anyone.
I'm still not convinced there's any elegant way to make the host character work well. I think player characters are bound to get annoyed with the host no matter what, either because they're not helping enough or they seem so helpful that the player characters aren't required.
My solution: Don't bother with a host character, or have them turn up dead early in the adventure.
The séances weren't great experiences for anyone. The messages from the ghosts are cryptic, with some being more useful than others. Then characters get to ask follow-up questions, which often can't be answered without spoiling the plot. It's frustrating for both players and Game Master.
My solution: Don't hold séances. Have mysterious cryptic messages traced in a dusty surface, or on the suddenly condensation-covered surface of a mirror.
Padraig, the Game Master running the adventure, did an amazing job of shielding us players from the tangle of plots happening in the house. We ended up following the Halvrest storyline, which I recall being the most confusing, but as a player it was relatively simple to follow. It was still difficult to solve, mostly because the séances were so useless, but the storyline worked well.
There were definitely elements that seemed superfluous, though. We found Dalk Dranzorg's axe early on, and we ended up encountering the chimney witch, and in the end it really felt like not a whole lot of what happened made sense in review.
My solution: I like that the adventure has the option of three separate plots, but I think I'd set each plot in an alternate reality. The Game Master ought to roll a d3 at the start of the adventure for a plot, and then only the hauntings that relate to that plot are brought into play. For example, if you're running the Halvrest version of the house, then the corpse in the tower wall doesn't even exist. Don't bother with it.
The biggest problem with the adventure is the stagnation before the house awakens, otherwise known as 98% of the adventure. It's really bad.
I honestly don't know what characters are supposed to spend their time doing before they manage to trigger the endgame. You wander around the house, poking at things, hearing ghostly voices but having no agency to do anything about them. You offer to help spirits but you get no answer. You try some very reasonable things to relieve a ghost's suffering, and everything you try fails because you didn't put the candle in exactly the right place when you lit it.
There was shockingly little to do in the house before it awakens, aside from wander around from room to room. But why are you wandering from room to room? You only do it because you know you're playing D&D, and that's what you do in D&D.
The result is that you level up maybe once. And then the house awakens, and you're fighting creatures that outrank you by several levels.
It didn't read like it was monotonous, but there's not quite enough adventure to this adventure. The plot points seem to be positioned wrong. They all happen at the very end of the adventure. I think the host character is meant to be used to drive the story, because without the host calling the players down for an hourly cryptic message from a ghost, there's just nothing to do. In fact, even with the host character there's no reason to do anything but sit around the parlour and wait for the spirit board to rev up again. But for the mists of Ravenloft, I think my party would have just gone out for tea between séances, and come back to solve the riddle at the end.
Padraig, the GM for my game, added encounters and tried to have the host characters interact with us from time to time. It helped a lot, but there was no way to shake the fruitlessness of exploring a house with no way to solve a haunting riddle that hadn't yet been revealed to us.
My solution: Reveal the full riddle (all the messages from the ghost) up front, and then provide leading clues (messages in dusty surfaces, and so on) as the characters roam around the house.
It turns out that House of Lament is no Death House after all. It's a pretty awkward adventure, but I still like the concept. It needs a lot of intervention to work well for players, and I think there are plenty of great ideas in it to serve as a fun haunted house sandbox.
I think with a Game Master who's flexible with the adventure could build something fun out of this. You'd absolutely have to reward players for clever attempts to solve a haunting, even if it doesn't match up with what the book says the exact solution is. I definitely wouldn't run this adventure as written, though, and I'm not likely to re-play this one.