Just played this and on the one hand, it was a good module, stretching people's role play skills to try to get some things done. That was really good.
The downside is that the fights are way out of control. Granted, we were a table of 4 playing high, and the middle fight was not too brutal. But the final combat is just horrible. Without a proper table balance, you will auto-fail, even if you have done everything right. Spoilers for the final fight below.
So, the final fight is with one human-possessing shadow demon and two babau. If you don't have anyone who can get rid of the darkness (And how many casters carry continual flame or daylight spells on a daily basis?) then only the people with darkvision can fight effectively. Worse, if any of the wedding party go down, you fail. So, somehow it's the Society's fault that we didn't expect demons to show up? If there had been only one babau and the shadow demon, that would have been tough but doable. Two? Not as much. Especially as most people are not going to be demon hunters or have cold iron weapons lying around. We had two people with them, but one couldn't see and got sneaked to death in the darkness. With four people who might be playing Cha-based characters, they might die from a non-crit sneak.
So, overall, I like the idea of the module, but the execution needs work. If you want to play this, make sure you have a full and balanced table.