Color of Madness adds an endless mode, that while I consider not that fun, is good if you like that sort of thing. Fortunately, it adds another way to interact with a lot of the dlc content by adding an optional wandering miniboss that you can choose to go hunt down, and it honestly gives you a goal and something to go after besides just leveling all your heroes up to 6 after you beat the game. The couple normal missions leading up to the endless are fine too, but the highlight for me is the miniboss, which, while difficult, isn't game breaking, and you can build a team designed around killing it because it tells you what area it's in so you can anticipate when you'll run into it. With drops from this miniboss, you can still get a lot of the trinkets and buildings this dlc adds, although at a slower rate, but it feels more fun and balanced this way, because it feels like I'm doing normal missions but with the added bonus of occasionally running into a challenging miniboss in the halls at random, you can't predict where it will be like a normal boss, but you can tell if you might run into it during your mission, so it's just the right level of preparedness and randomness, and it doesn't really detract from the base game at all, it still feels like darkest dungeon but now you have a strong miniboss that you may encounter if you want to go to the specific area it's in, but with great rewards and not impossible difficulty. Honestly, this dlc just adds to the game, and if you do interact with the dlc content you will be rewarded for it, and if you don't, well you don't actually have to interact with it, it's not forced on you like crimson court.
Edit: This dlc also adds many minor additions to the base game, like some new quirks, some of them just added to the basic quirk pool you can get from normal curios or mission ends, some pretty good, some fairly bad.