Honestly not as bad as I was lead to believe.
Theresa's story is fine. It's always cool to see events unfold from a different character's perspective. This felt a lot more like an interactive novel in the same vain as something like TellTale's Walking Dead or something. There's a lot of talking and walking interspersed with moments of action or stealth that's a little bit clumsy but gets the job done. There's not a section that stood out to me as egregiously bad, though that may have been because of my choices. I will say there's some clever bit of environmental design the devs use to guide you if you're ever feeling lost and the dog is very handy at showing you things of interest.
I did think it was lame how little Theresa gets to customise herself with gear, but really she's a Miller's daughter. She has no combat experience so she's not too great with a sword and most of her gameplay revolves around stealth anyway. Less clanky armour is good in this case. I dunno, if you like KCD's story and want to know more about its world and characters go ahead and play Theresa's story. I think the problem with this DLC is that it had to happen in a very specific way. We've already seen what happens from Henry's perspective, so whatever happen's in Theresa's story must eventually align with Henry's. And unfortunately that means letting poor Tinker die.
Johanka's story is the more engaging one. It has cool moments where it remembers your actions not only during the side quests within the story, but also some of your actions in the main game too. There's a lot of side questing with varied objectives and gameplay and it all culminates in an intense climax. I got surprisingly invested in Johanka and with the context from Theresa's story, I came to root for her even more. I'll be honest by the end I was so upset that I had to step away from the game for a bit. It's worth getting the DLC for this story alone.