For extra entertainment, note that the Amazon listing has the description for a completely different PPP book. I kind of wonder how many potential purchasers who are bright enough to be able to tell that 91 AD Roman Britain is hardly "medieval" have been turned off by that in the past.
Incidentally, I just finished reading #3 in the series (available for $2.99 or less in several venues as described above) and it was another nifty read.
These things come with interesting historical background/culture notes and discussion + suggested bibliography/further reading for people like me who find such bonuses doubleplusgood, by the way.