I rode this last month. I was going to do a full TR on my visit but can't be bothered now, but will throw in a few Danse Macabre thoughts...
-It's a wonderful experience all round. It's a piece of theatre.
-The ride system is loud. The whirring could almost be excused as "ghostly noises", but nah. It verges on distracting.
-There's a lot to see and to take it. It is a ride you have to ride multiple times. But I wonder what it's like after you've ridden it 10+ times and seen it all, does it lose some appeal?
-It's very much not a post-lunch dark ride; something I only really learnt after riding it after lunch...
I don't see this ride system being used in many places, if anywhere else. It's a staff-intensive experience: they had 6 staff for checking lap bars (one for each gondola), who thus spend most of the time doing nothing. They have an operator and a batcher. That's a minimum of 8 people needed for the ride to run anywhere near what you would call efficiently. They also had extra staff in the queue / at the entrance. It's, surprisingly, no more than what they have on Max + Moritz. Which is why I don't think it's an issue for Efteling. But can I see any other places, outside of maybe Disney or Universal, being able to sustainably run something like this efficiently (as well as actually craft an experience worthy of the ride system)? No.
Anyways, this is an absolute win of a ride. As someone who didn't care for Spookslot (only did it once), this is a much, much needed improvement to the park.