There's lots to enjoy with the novel, but unlike in Swallow's previous stories nothing really stands out. Among the positive content that still felt like it could have been
more: the Kriosians. Using the Kriosians was a pleasing choice; they were (sort of) already established as a Klingon client race (I much prefer the "all uses of Krios are the same world" idea to the "two planets" idea, which KRAD hinted at but I don't
think ever explicitly confirmed..) and we know enough about their history to want more. That said, they ended up being rather generic. That's not a complaint about the characters among them, who were perfectly interesting, only that there wasn't that much to mark them as Kriosians particularly (some interesting notes about their people's history of resistance aside). Then again, Kriosians weren't a particularly alien culture to begin with, were they? They were just proud colonist-monarchists, with spots, and with a pretty stratified social order. So while the Kriosian characters could have been of any race really (again, those references to Krios' independent spirit deserve mention, but weren't particularly defining of this one culture), that's probably more Swallow being true to what we've seen of them than anything else. Still, Thorn-as-Kriosians did feel a
little like wasted potential.
On the other hand, the Thorn-as-a-terrorist-resistance-group
was fully successful in my view. Their portrayal avoided both heavy-handed villainy and overly sympathetic softening. Their cause was logical, their attitude sensibly antagonistic, and they avoided being any sort of commentary on any real terrorists. Swallow did very well here.
I liked the use of subspace weapons again. I think the only other novel to explore them was
Serpents Among the Ruins, and we do need to see them, I think, to justify why they're so frowned upon. Also, Vaughn's always good to see. There were a couple of nice continuity references to those relatively few things previously established about his early career and background, and the tale of his first major success for Starfleet was something I guess many of us have been wanting to see.
I actually don't really mind another Klingon tale, though as others have said the setting makes it hard for the novel to stand out. It's certainly true that Klingons are overused and a bit stale, but given the nature of their society and culture it doesn't bother me that they keep flaring up. There's always going to be some sort of trouble in the Empire. And this particular point in their history was underexplored - we've had the immediate fall out of Praxis's destruction (as well as plenty of stories leading up to the event), but our next exposure to Klingons was set in 2311, when they were recovering and Azetbur was losing power. 2300 is a good mid-way point between Praxis and Tomed.
I suppose I'm a little torn, basically. Klingons are used so often, but the idea of yet another Klingon issue isn't unrealistic, because these
are Klingons we're talking about. We also had another barely-prevented major attack on Qo'noS (remembering the strike in
Forged in Fire)
, but, again, this
is an unstable empire that has enemies all over and considers internal conflict a normal part of life. So the "we've seen this before" complaint rings a bit hollow. Still, it does lurk in the back of the mind. Swallow's writing is always good, so that certainly helped keep me interested and keep the lurker at bay, but I do agree that Klingons might be just too over-used to let this novel carry the weight it should. Not really Swallow's fault, but it makes his novel have to work harder than it should to be more than average.
On the other hand, Swallow does try, I sense, to offer a little variety. There's good use of a range of Klingon ship designs, rather than simply Birds of Prey or
K't'ingas. And one short scene features a
Yan sword rather than a
Bat'leth. Those are only little details, but they did help raise the Klingon depiction out of the standard fare a little. I suppose while I'm on the subject, we also get a reversal of sorts with Kaj, in that in previous stories featuring Imperial Intelligence (KRAD novels, mostly), II is usually less sympathetic than the Defense Force. Whether it's Qaolin in
The Art of the Impossible or Klag in the
Gorkon stories, the Klingon we're rooting for is usually the fleet officer, and the II agent is rendered an antagonist of sort. Here, it's Kaj towards whom the story is favourably biased. On top of that, her crew including non-Klingons was a nice touch. So overall there was an effort made, I feel, to twist the Klingon setting around a bit.
A few little notes: we got a name for Chang's BoP, which I believe is taken from the novelization of The Undiscovered Country -
Dakronh. We get a little of Chang's backstory, too, which I believe is all original, and welcome. While we're on Chang, the line "Let's keep the Shakespeare appreciation to a minimum" did make me smile.

Another character thread followed up on was Nanclus - I'm glad, because he was always a bit of a loose end. Maybe he got tied up a bit too neatly, but I liked Kaj, so I didn't mind Nanclus' comeuppance at all.
Random continuity point: I believe this novel marks the earliest chronological apperance of a Grazerite. On a related note, the Federation and its starfleet are nicely diverse - we get Cygnians, Andorians, Rigelians and Caitians rather than just Humans all the time. This diversity is always a good thing in my book.
As for the cover, I agree it's misleading, but it's not, I feel, a bad cover if you take it non-literally. I know most people would take Spock's picture as an advert of his being in the book, so I agree it's a bad choice, but I thought it actually worked quite well thematically. Valeris indeed doesn't cast a shadow because she
was the shadow. She was Spock's student and subordinate, quietly lurking.