After reading vol. 1 thru 4, I could barely wait for vol.5, and now, after reading it, I wish I had waited until the final volume had been released, to finish them both together.
I say this because at the end of Vol. 4, I was in a good place. Happy, so far, with all that had happened. The problem of the virus had not yet been solved, but it left me with most of the major characters safe, for the time being, and I could live with that.
Then vol. 5 was released, and I grabbed it immediately, read it no time at all, and did not like the way it ended. So now I'm frustrated, with myself, not the author. He wants me to be hanging by a thread, waiting for the final episode. But I'm not good at waiting. So like a spoiled brat, I am frustrated right now.
I still think this is one of the best sci-fi I've read in a good long time, and highly recommend it.