I found the base game absurdly addictive and fun. That was back when the Jester was still a bringer of destruction (using Solo/Finale several times per battle!) now he is mainly a stress controller and party buffer. Even so, there is so much variety among the heroes, you have so many party configurations that can work that it never seems to get old, and the more you play it, the more ways you find to use some of the character abilities that you may ignore early on (for me it was moves such as Crusader's Bulwark of Faith that I love to use now). Also realizing that several trinkets are well-worth the stress penalty was an eye-opener for me (I had conditioned myself before that that everything that increases stress must be bad, I was wrong). They have better balanced a lot of the character skills since before, but is it better? I don't know if it's better, but I like it every bit as well now as I did a year or so ago.
As for the DLC, well, the Crimson Court is great if you want a totally new and awesome hero to play in the flagellant. He plays rather differently from the other heroes and that's emblematic of the Crimson Court overall I think, since the Courtyard region it adds plays so differently from the standard DD regions. I thought it was well-worth the asking price as it adds some massive Courtyard areas that challenge you in a new way compared to the base game, and it also gives you a hero and a pair of unique, story trinkets for each hero in the game that combine to give an extra bonus if used together.
Shieldbreaker? I guess I'm in the minority in that I thought it was a pretty good add-on. Obviously the biggest part of this DLC is the hero herself, but the new enemies are interesting, though rare outside of specific occurrences in my experience. Her abilities are really helpful and she gives you another mobile hero that is good in any rank and can quickly reposition herself while still using a skill. I love the game overall so for me it's worth it.
Color of Madness? Remains to be seen, but Redhook continues to tease this new DLC and it appears as though it will play differently from everything else. I really appreciate that they continue to support and expand the game, so I'll keep checking in on all they do here and keep on traversing the dungeons.