Oh, early Star Trek: The Next Generation books, how I love thee. I couldn't get ENOUGH of TNG when it was on television in the 80s and early 90s. Of course, I was young then, so all the nuances I missed actually makes rewatching the show fantastic. However, the same does not hold true for the books. I read this book when it came out, and I loved it. I was wrong.
Peter David is a hack, pulp writer, and I'm sure he knows it. Perhaps his novels have improved since 1991, here is hoping. I'll never know. But one thing is abundantly clear: this book is terrible.
The characters are all wrong. Data is an automaton with no personality. He doesn't care to figure out humans while expressing his interest to do so in only a verbal fashion. Picard is closer, but much more emotional, even taking in account the Borg. He's always shouting or slamming his fists on the table or otherwise losing his cool. The rest of the characters, especially Worf, are cardboard cutouts. Almost jocular, their conversations are much more casual than you'd expect from them. Worf glowers menacingly at everyone and wants to shoot the phasers. That's it.
This is even worse with the side characters. Captain Korsmo, Picard's Starfleet Academy rival, is so incompetent and driven by jealousy it's like he has no other qualities. The disregard for the lives of his crew, the crew of the Enterprise, the whole of Starfleet, and basically anyone including himself is shockingly unbelievable.
In fact, only the Borg are characterized well. And that's because they are single-minded consumers and don't talk much.
Then there are the glaring plot holes, the jarring structure, and flimsy references to the Technical Manual as the stopgap for being creative in any way. At one point, during their pursuit of a Borg cube, Cpt. Korsmo asks Shelby how to fight the Borg. As if every Starfleet captain wouldn't, at this point, been briefed. Korsmo especially, since he KNEW he would be fighting the Borg and had Cmmd. Shelby as his first officer. But no, let's wait until we're actually FIGHTING the Borg to get that info. There are several scenes like this that either don't make sense because the characters have no grasp on reality or because the author literally forgot what happened in a previous scene and has characters act contrary to what they discussed earlier.
Still, there are two things that shine in this novel. As I mentioned before, the Borg. They are terrifying still. Single-minded, powerful, and implacable, they smash through almost all opposition, and when they don't, it's pretty satisfying.
Second, Delcara and her Doomsday Device. Miles long with an impenetrable hull and a weapon that destroys planets, she is formidable. A fine antagonist for the Borg, and a fun foil for Picard, she really shines. Insane, and nigh relentless, it is her love for Picard that ultimately destroys her.
I usually end up rooting for the villain in stories that have no real substance, because the villains tend to be more interesting. So, I'm always sad when Delcara meets her, somewhat ambiguous, demise. Certainly her insane drive to destroy the Borg led to her death, as one expects, but it would have been a much more interesting story if she had managed to go out in a blaze of glory instead of in a haze of love. Especially love so barely defined and pathetically described.