I would call Unspoken Truth
an average book from MWB and a better-than-average book overall. I loved getting a better look at Saavik's psychology, background, and adopted family. I also loved the worldbuilding involved with the Deemanot. The plot and tone seemed to take a sharp turn when Saavik left the retreat. The spy story was still enjoyable, but it wasn't quite as interesting as what came before. The end sequence explained a little bit too much for my taste. Chapters 18 and 19 could have been essentially removed from the book. I still would have gotten the basic idea of what the V'Shar, Romulans, and Saavik did, and I could have spent more time reflecting about the details of the operations.
This may have little to do with Margaret's work, but both covers for the book are terrible. The blurb on the back gives far too much away, and the front cover image is completely unrecognizable as anything but a generic futuristic city. I don't demand a rendering of Saavik, but the actual cover has no thematic connection or obvious tie-in to the story being told.