After the long slog that was the previous novel, I was very glad for the page-turner that is "Nightshade." Creepy without being outright scary, this novel held my attention even though cough syrup with codeine - a major feat.
There were many likeable characters in this book, although none were drawn very deeply. I didn't feel like I could identify strongly with any of them. This did have a bit of an impact on the way the book affected me, in that I didn't care too much about any of the characters who died.
One thing that struck me was that this was a story that could have been done on television, although it would be much better done with today's technology than that available in the 80s. This novel didn't so much push the boundaries of what was possible as go "back to basics" and throwback to what Doctor Who had been fifteen years earlier, with a nudge forward in what would have been required for visual effects.
The solution to the situation was rather interesting and seemed to follow naturally from the ideas on which the book was based. The characterization of the Doctor and Ace was solid. While no one could call this a romp, it moved quickly and steadily forward with moments of humor sprinkled here and there.
All in all, I'd call this a solid effort. It wasn't high art, but it was satisfying and a good book to read while I recovered from the flu.