I picked up a copy of this book and read through it.
It's also good to remember that it definitely did destroy the planets, albeit nowhere near as violently as Alderaan was destroyed; it had to batter down some of the chunks left with further shots to leave them in small enough pieces for the ship to digest for fuel, but the initial full power beam did crack the planet up.
Nowhere is the planet killer described as cracking planets apart with one shot. There are several descriptions of it methodically slicing chunks off planets and tractoring them into its maw. It can do this in about half an hour. That's pretty impressive, in many ways moreso than simply blowing a planet up - the rate at which chunks have to be split off and fed into it is extreme. The power plant is an unspecified method of total conversion, but the sucked up matter is converted into energy instantly and stored in some extraspatial form, rather than kept around as hyperdense fuel and converted as needed.
The maximum sustainable speed of this model is warp 7; the maximum speed of the prototype is stated as warp 4. Range is something like 10 light years between planet consumptions, with the capability to store at least ten planets worth of energy at any one time. The 'subspace interference' communications blocking effect is an unavoidable product of its drive system and extends for several light years.
The ship plunged directly into a star at warp 7, went right through the core at low FTL velocities, then came out the opposite side and warped away glowing white hot but with no other damage. That's
extremely impressive, particularly considering that the ship has no shields, so the superdense plasma was resisted by the hull alone. It does have a 'transporter field scrambler' that can be lowered as required; the hull itself does not block transporters. The Ent-D initially can't scan through it, but after messing about with their sensors for a few days they manage to get a partial scan of the interior.
That said its combat performance against the Borg is rather less impressive. It is not invulnerable to borg weapons; they create 'carbon scoring' on the hull, and the second borg cube it encountered managed to blast a 'small chunk' off the hull before it was destroyed. The Borg shields fail to work at all one the first cube, but the second one survives the PK's beam plus the Enterprise firing everything it has for a couple of minutes. The pilot expects that facing three at once will be 'a difficult battle', and this appears to be correct; the three cubes shots cause 'cracks in the neutronium hull to appear' - which then leak 'miles long streams of energy conversion plasma'. Worf calls this 'considerable damage' and predicts that the PK will lose if the Enterprise and an Exclesior class ship don't help. The damage to the PK brings down the anti-transport field, the borg beam over and the thing is revealed to have no internal defences at all - the borg use a phaser to drill through the crystal block and mortally wound the pilot within seconds (they only fail to kill her outright because Picared kills the attacking drone). The PK does have a highly effective self-repair capability however, which can fully repair the vessel within hours but at a very high energy cost.
The ship is described as completely immune to Federation weapons before the outer hull is damaged, but slightly vulnerable to them once breeches are made in this by the borg.
Incidentally this book has painfully bad references to bits of the TNG tech manual (warp physics mainly), distorted into sounding incredibly stupid. It is also
extremely minimalist about the size of the Federation fleet ('most of the best ships and crews' were lost at the battle of Wolf 359, and Starfleet cannot assemble as powerful a fleet again a year or two later, even given plenty of time) and travel times (Federation, Tholian, Romulan and Gorn space are all only days of travel time apart at warp 6/7).
It also explains the deflector shield trick as a specific 'frequency of energy' that the Borg systems were vulnerable to. It didn't work because they fixed the problem after they assimilated Picard and realised that the Federation knew this. Of course it's pretty sad that they didn't notice the problem themselves. Another Fed ship uses the deflector shield trick in the novel and it heavily damages (but doesn't destroy) a Borg cube that was too distracted to adjust their shields to resist it.
The author also uses a tactic you'd expect to see coming from a Trektard; weaponising the 'static warp field' effect that Crusher got trapped in. This is so impressively idiotic it deserves recounting;
They upgrade the 'emergency antimatter generator' to act as a high-output M/AM reactor that takes a 'special mix of matter and antimatter' and generates an energy pulse that is channeled through the warp nacelles (this only works at impulse). This interacts with the 'subspace field' of another ship (which is also at impulse so this could be the mass lightening field, shields, intertial dampers, who knows) and converts it into a warp bubble that takes the whole enemy ship out of normal space, then shrinks and destroys it. From the scene where this idea is brainstormed;
"How long would it take to prepare the emergency antimatter generator?" asked Picard.
"Wesley did all the the theoretical groundwork when he was first doing his experiments." Geordi shrugged. "This is just a straightforward application. Maybe half an hour."
On the plus side, this does not actually work; all it manages to do is take a borg cube out of the fight for thirty seconds or so.
The method of destroying the PK is pretty sucky, in a 'Threshold' kind of way. The pilot decides to try to reach borg space before she dies and overrides the engine safties. The ship accelerates to warp 9.9 normally, then jumps to warp 10. This traps the ship in some sort of time loop as well as putting it everywhere in the universe at once. There's no way for her to deccelerate or otherwise get the ship out of this state.
The Duchess of Zeon wrote: The captain/controller of the Vendetta planet killer intentionally tractored a borg cube inside the maw of her vessel and then fired to destroy it, simply to demonstrate to Picard that the weakness no longer existed. Yanking around a borg cube like a play block and then blowing it up inside your own vessel simply to show to someone that a technical deficiency had been corrected is an impressive display of capability.
I've read through the whole novel and this scene does not appear anywhere. Maybe you're thinking of that Voyager comic that features a doomsday machine. A borg cube is eaten whole near the end, but it is heavily damaged ('33% functional') and the Enterprise is helping to push it in (with tractor beams on repulse) as well as the PK's tractor beam pulling. The borg cube explodes in the mouth and fuels the PK's auto-repair system.
The borg fully adapted to its weaponry AND sent like 10 - 20 "super cubes" made out of combinations of multiple of the normal cubes at it, and these were the early TNG borg being shown,
No, it sends one cube, then one cube, then three cubes. Which were a few kilometres in size, comparable to the one in First Contact.
and despite all of that the sole damage to the ship came in the form of a small "scar" in the armour which was immediately and automatically sealed over by some form of liquid from inside the vessel,
No, they did very serious damage, and if the three Fed ships hadn't helped out the PK may well have been destroyed. By three cubes. That's actually fairly pathetic for a weapon that's supposed to anhiliate the borg. Yes it could auto-repair that damage given time.
when every single borg ship AND the Enterprise had concentrated all of their weaponry on the same exact spot, after literally days of battering the thing,
Now you're just making stuff up. They don't battle it for days. They don't concentrate fire on the same spot.
In the meantime I lost count but I think that it took out like 30 Borg Cubes of regular size and an equal number of Tholian ships, or more, never once being able to dock for repairs and constantly being hounded.
When did you read this novel again? There were 3 borg cubes. It was attacked a few times over a week or so. Each battle was relatively short. It was not 'constantly hounded'.
The full production version of the Doomsday Machine, as seen in Vendetta.
It is the only one built; it is explicitly reffered to as 'the last surviving artefact' of the race that built it, their one great hope, their great weapon etc.
If anything bad happens to my body, it will encase me in crystal, neurally linked to the ship
It will also drive you utterly mad from the thousands of Preserver intelligences demanding that you obey them. A super-strong-willed member of Guinans race couldn't resist them, you definitely won't be able to.
The neutronium hull should stand up very well to what can be thrown at me by conventional ships
If the borg can breach it I doubt TLs will have much trouble.
the suicide ramming down the maw option was fixed from the prototype
True.
nd it's small enough that it can't be easily targeted by anti-planetary weapons.
False. It's tens of kilometres across, and throughout the novel characters mistake it for 'a small moon' (silly I know).
Warping into Coruscant space and nailing them before they can raise their planetary shields to kill the Emperor
I very much doubt this will work, as SW has subspace sensors and this thing only moves at ~2000c.
