^You mention in your review how little was added to the adaptations. The first few Blish volumes took a lot more liberties with the stories, adding some interesting new ideas; for instance, it was in Blish's "Tomorrow is Yesterday" adaptation in Star Trek 2 that 40 Eridani was first proposed as Vulcan's home star. But the later adaptations became much more screen-accurate, largely due to complaints from the fans (yes, Trekkies have always been complaining about continuity). Also, I gather the later volumes were largely ghostwritten by Blish's wife J.A. Lawrence, though I'm not sure how extensive that was or when it began, if it's even so.
I'm doing an ongoing marathon read of Trek books, so I'll be reading more of the Errand of Vengeance/Fury books as well as many more TOS era books.