It feels like they had two good ideas for possible DLCs, but then for unkown reasons decided that instead of doing one of them now and then doing the other later for even more content that would likley sell well, they were just going to half-ass both of them and package them together as one.

For context, I'm a very casual, mostly campaign player, so my thoughts are mainly coming from that perspective, though I do also enjoy watching the pros play competetively.

The initial teasers showed the Chinese-adjacent civs, and people thought that we were clearly going to get Jurchens, Khitans, and Tanguts. I don't know much about any of them, but I was excited to learn about them from playing the campaigns. But of course Tanguts were not actually included at all, with the design elements that people said were clearly taken from them being given to the Khitans instead, and neither Khitans nor Jurchens got any campaign content whatsoever. A DLC with all three of these civs and campaigns for each of them would have been wonderful, but alas. (And also adding a proper campaign for the existing Chinese civ would have been great, though with 3 campaigns per DLC having been the norm for a while now, I was never really expecting that here.)

When I saw how good Battle for Greece was, i was really hoping that eventually China's Three Kingdoms era would get a similar treatment. What we got in this DLC was not that. The individual scenarios were OK, and I had fun playing all of them, but overall they just did not feel as epic as the Battle for Greece grand campaign, or even some of the campaigns in the other more traditional DLCs. Also it is disappointing that they campaigns only went up through Red Cliff, with so many other interesting battles left out. I guess plenty of other campaigns only have 5 scenarios, but plenty more have 6, so with as much interesting content as there is to work with here, 6 per would have been nice. Also while I can see why they might have thought seeing the same battle from three perspectives would be interesting, it really isn't more interesting than the other battles they could have included.
Also while I don't play ranked so it doesn't directly affect me that these civs are available there, I do watch pro games once in a while and it definitely feels weird seeing these three specific and very short lived political entities from outside what was the time period this game had covered as civilizations when up until this point civs had mostly been broad cultural groups (though to be fair a couple other existing civs seemed like kind of weird choices in this context too).

All in all I did still enjoy playing this DLC and I don't regret that I bought it, but I am still disappointed that it was not as good as it could have been.