Alrighty, finally finished it.
Man Takahashi knows how to pull on those heartstrings. Milton's death does add some perspective on why Mythra chose to renounce her powers, as well as capping off her arc of going from being ambivalent towards people to learning to care.
Also that zoom through the forest from Lora and co to the advancing Indol army, knowing what happens next, hit hard. Her death was already a moving scene in the base game, but next time I play through it, having gotten to know her better, it's really going to hurt.
I could've done without the final fight with Gort though; while I get its narrative purpose, to illustrate that even with Malos gone, there are evil people and because of them strife will continue, it still felt anticlimactic.
Haze saying she couldn't imagine being the blade of someone as horrible as Amalthus, only to go on to become as such in the main game with no memory of her time with Lora and Jin, not knowing that the former of which, who she so loved, was murdered by her current Driver, was also a poignant moment. Again, adds another dimension to the scene where Jin kills her and says "you're free now".
Finally, the flash forward to Rex that give Mythra the power to vanquish Malos, and the DLC ending with Rex finding Pyra, was a really cool tie-in that I liked a lot.
All in all, liked the expansion quite a bit. Yeah, it does make the Aegis War seem smaller and shorter than the main game seems to imply, but the extra character background and seeing key moments that were only implied in the main game really does deepen the the overall story's emotional impact.