I just spent all day yesterday and this morning burning through the entire manga after I saw you post that link on Facebook, Pyske.
I'm on information overload right now, but I can say that I really enjoy this manga. I read through some of the comments here and am surprised at the frustration that some of you have shown with this series. I guess that's just the benefit of having the entire thing available to me at once, rather than waiting for updates.
I think my favorite aspect is the change in scale of the story. At first I assumed (from watching an episode of the anime) it would be quite insular, concerning only the main characters and their psychological issues. I was taken by surprise once it grew into a full-out apocalypse scenario and fight for humanity.
I really like the current set of characters. I really enjoy Kei's relationship with Tae because it felt like a natural progression of affection. I'm glad that Kato was brought back. He's my favorite character, and I think his motives and thought process are in line with some of the major themes of the entire story. He's not the protagonist, but I would venture to say he's more important to the story than Kei is.
The only thing that bugs me is the unsurprising lack of strong female characters. I guess that's par for the course when reading manga, but at the very least I would have much rather had the kickboxing girl Kei lost his virginity to survive than Reika's sorry ass. Even Tae started off likeable (and not particularly pretty), but now she's become fetishized. All those panty shots are giving me grief.
I hope waiting for new updates isn't too tedious.