It still retains the flaws of the previous books, but it's an entertaining read nonetheless. Aside from whatever problems this volume maintains from its predecessors, the only other problem I have is that this volume doesn't really feel like an ending.
It's the last volume in the main storyline (as far as I know, unless there's some sort of obscure fifth volume I don't know about), but as far as appropriate endings go, this doesn't seem to have resolved much. I mean, the main characters struggle to prevent a fourth world war, but it doesn't feel dramatic like an ending should. Maybe I'm just too used to big, dramatic, dynamic finales where every other line MUST be said with an exclamation mark at the end and gun battles are more intense than ever, and revelations are made and... whatever. Hollywood has gotten to my head, which isn't a good thing.
It's clear Masamune put a lot of effort and care into these books, and everything seemed a little more cohesive this time around (and a lot less down-your-throat philosophical), so that earns it an extra star. It's a great read. All the books are great reads, but this one is probably my favourite volume of the pack.
I wish there were more of them.