I agree with that sentiment. XL is great for Liu Shan's character for a couple of reasons but above all, it shows he wasn't cold and callous about his wife's death as it originally seemed that she was killed in the original Siege of Cheng Du stage. Granted, it did make the ending a bit sadder in that regard. Other stages that really stood out were Xiahou Ba's Battle of Taoyang. Koei tried to capture that feeling of desperation and they really succeeded (on harder difficulties). Xiahou Ba's attitude completely changes for this fight as he looks frantically to escape and doesn't give much thought to anyone there to rebuke him as he knows their end aim is to kill him. And the cutscene at the end where he comes to a sudden realization that this all happened because of his killing of Guo Huai was quite a powerful moment.
I had hoped for all of that to be expanded upon in DW8 but not this time around, I suppose.
Wang Yi's character was great, I thought DW7 would be a "preview" for the XL characters and in someways they were (except Pang De's role in Dw7XL is much larger than in 8 unfortunately) Guo Jia's fantastic characterization only gets better in 8. I must say that I really enjoyed Xiaoqiao's stage. Just something about her attitude makes her a lot of fun, I'm not sure why people seem to dislike her.
Overall an incredible expansion and I can only hope 8XL continues in that vein of vastly improving the base game (which from what we've seen seems like it could be likely)