I figured out how to sum up my feelings on this one. Full spoilers:
I really liked the first 24 chapters and the last 26 chapters. I just didn't like them together. I like stuff like this, where the protagonist "changes" in some way, and has to explore and understand themselves anew. But the timeskip felt like it ended the original story too early and started the second story, which was too disconnected from the first. And there's about 10-20 chapters missing from the middle, somewhere before chapter 24, that would actually explain and explore Okazaki's feelings for Nora and Yukiko, because his relationship with Yukiko was something that I expected to be explored as he became more of a vampire, but they never spoke to each other except in passing after a 20-chapter (and ten year) hiatus. And you could call it a "kin" relationship or whatever, but Okazaki got over Nora ruining his life way too quickly. For that matter, Okazaki went from being the main character to being a cameo deus ex machina at the end, which was incredibly disappointing. We never saw any of what happened to him in the facility, and he wakes up ten years later entirely unchanged. He's even wearing the same weird restraining getup.
I didn't care for the cult leader, but it's whatever. He made for a pretty 2D villain. And it was never really explained how Yukiko survived the knife attack? I was expecting her to have some latent vampire in her towards the end from Yuki licking her wound but that never happened. On the matter of plot holes, why exactly is Saku envious of Okazaki early on for being able to die? Yuki was a vampire for ten years and (presumably) drank blood all that time, he should be a full vampire. But having his brain be eaten was enough to kill him. Vampires don't seem to be any more resilient, they just have unlimited healing and cannot be killed, so it shouldn't be difficult to have your body and brain ground up. Feed it to some animals if being digested is necessary. It just felt like a bit of an asspull to claim for so long that it is literally impossible to kill a vampire and then to have Yuki die.
Nora being cut up into pieces and surviving as just a brain was genuinely unsettling, though, and the author has my respect for that.