The most jarring bit for many people not conversant even in passing with the earlier iteration of the novels is the Klingons and their urgent search for a particular substance on the planet.
Basically at this time some authors had established that without a kind of drug Klingons were incapable of controlling their violent urges, and the crew of this ship had run out some time ago. It's like a less intense version of ketracel white basically.
I don't remember any books asserting that about the Klingons. And once you get to the end of Doctor's Orders
, you'll see that things aren't always what they seem.