This novel is an adaptation of an episode in the "Next Generation" television show. It is well-written, and any flaws in it are not truly the fault of the author, Michael Jan Friedman, but rather of Ron Moore, the writer of the teleplay for the episode it was based on.
My primary objection, perhaps surprisingly, is not the method of justifying (or even the very fact of) the existence of the character of Montgomery Scott nearly a hundred years after the original Star Trek series; I found myself willing and able to suspend disbelief for that concept. No, what I found troubling and implausible was the characterization of Mr. Scott, and his inability to recognize what he knew, and what he didn't, and to avoid being a danger to everyone when let loose in an engine room.
The man was no fool, and perfectly aware that technology had changed while he'd been "away". And he'd plenty of experience examining unfamiliar, superior technology. He'd not have made the stupid mistakes he was portrayed as making. Nor would he have failed to understand that a chief engineer can't be interrupted while on duty. The entire concept, essential to the story, was an insult to the character. Other than that flaw in characterization, the story was good, and it was a pleasure to see Scotty back in action. I just wish that the creator of the story had had more respect for the character.