I really liked the first Science of Discworld, and enjoyed the second as well.  I’ve always liked the idea of mashing up educational material and fiction - here it’s loosely interspersed (odd chapters are lightly educational, even chapters are a related Discworld story), and I thought these were fairly well done. This one, however, wasn’t that interesting.  I chose to read it now because of the Darwin anniversary stuff that was hot recently, so it seemed somewhat relevant.  The history was interesting, but the science wasn’t really.  The Discworld story was ok, but that part of the Science books has never been stellar (certainly not as good as a regular Discworld novel). It was good enough that I’d still check out a Science of Discworld IV, but I’m not hanging out for it or anything.