4.5 stars. Took me a while to get round to this one, as the second book wasn't great. This one was a couple of years after the last book, so I suspect the author spent more time looking at the pacing and story arc.
Whatever he did, this one worked a lot better than book two, and kept my attention once I started. It's not a fast-moving book, a lot of attention paid to the survival aspects, but if you're in the mood for that it goes pretty well.
One thing that detracted however was the formatting. I have no idea if it was just my Kindle or the file itself, but there were multiple places where it looked like an entire page or more was missing. Nothing absolutely crucial was missed, but it buggered up the continuity. I won't ding it a star for that, but if the author sees this he should fix it ASAP.