Once you start this DLC you NEED to finish it. You can dance around the other DLC(Color of Madness) if you're stubborn and Butcher's Circus is completely optional. This is not. This is a 'I beat the game and want to do something new!' not a 'this will integrate well with my experience once I start getting level whatever heroes consistently and master some mechanics'. I will show up at your home on my hands and knees begging you to not enable this DLC until you are endgame or near it. Monsters from this DLC can appear in other dungeons and while it's not guaranteed the Crimson Curse is pretty easily transmissible, and it's effect are very hard to deal with when your roster starts getting more and more infected with limited supplies to deal with it. Frankly it's really easy for Crimson Court to overwhelm your game, even softlock you.
I started it on a file where I had already beaten the game and I actually found it really engaging. A infectious disease DOES spread like wildfire, it DOES make sense close quarters might spread it, disease spreading rampantly and dominating my town DOES make sense to me, you DO need to mitigate or treat a disease and it's more negatives than positives(unless you're metagaming and optimizing). I though it was very cool. I thought the enemies were very cool. If I was unfortunate enough to play it early-mid game I can see it completely ruining things for me. The repetition is also an issue and I personally really hate an invitation mechanic. It forces you to grind even longer for a chance at progressing the plot. I would get this on sale exclusively AFTER you've beaten the game or are at the endgame.
Generic tips and tricks for the interested:
-Please don't do it man, take the left mouse button off your finger on the DLC enable screen man, it's not worth it yet. Beat the game or get to endgame first
-Be prepared for the Crimson Curse to dominate your roster eventually. I kept a dedicated team to rotate in and out with strict placement to avoid the spread, flat out fleeing combat with anything that might infect others
-The Flagellant is a very interesting and cool new character to have on your team. I think his presence alone made the DLC much more engaging
-There are certain trinkets that are borderline mandatory to defeat the last boss, and there is not a guarantee you will get all of them before having the opportunity to fight. Be aware there is an optimal way to do it