David Mack said:
There are three principal reasons why the Defiant was unable to scan for Prynn's DNA after the incident at Nahanas, and why Vaughn would have taken the report at face value:
1. The explosion damaged the ship's primary sensors. (On p.89, Bowers has to patch in the backup sensors.)
2. The composition of the comet had fouled their scanners in the first place; now their external sensor arrays are coated in the junk, and the area around the Defiant is filled with a cloud of sensor-fouling dust and debris.
3. Because Prynn would have been at the flash point of the blast that detonated a comet, it's unlikely any organic material would have survived. Try scanning for DNA at ground zero of a nuclear detonation.
There's also the fact that they were able to scan the runabout and detected only Taran'atar's life signs (since Prynn was in the transporter buffer), so they could rule out her being on it (or so they thought).
Smiley said:
Hey, we should consider ourselves lucky that only one canonical character died this time around. The rest of the Knife's fury fell on newly-created characters.
Yeah... I found that Dave's reputation actually helped up the suspense, because you believed that any one of these characters might actually not survive. So it was kind of a surprise twist when they did.
Another twist was the revelation of who the mystery woman from
Fragments and Omens was. (Spoilers ahead

The hints seemed to make it so clear that it was the Intendant, and for most of this book that perception was being reinforced... and then we get the surprise revelation that it's really Iliana! As for the Cardassian Woman, I thought "Iliana" as soon as the Klingon bounty hunter thought that she looked familiar. But it turns out to be more complicated -- there are two Ilianas? Hmm.
I have to admit that in Kira's vision scenes, I totally failed to catch on that her "generals" were doppelgangers of the main cast until the part where Kira was back in her own self and saw the vision from the outside, recognizing that "Jamin" was a ringer for Sisko. I missed the anagrams too.
As for the revelation that Taran'atar's mind-controlled somehow undermining or simplifying his character arc, I don't agree. On the contrary, I think it adds more depth to it. As we saw in the text through his inner debate, it wasn't as simple as him just growing beyond the Founders' control, because that would've gone against his whole identity and value system. This sequence of events, where he finds himself forced to obey someone he doesn't want to rather than obeying the beings he wants to serve, forces him to question that obedience, to recognize that he has been essentially a slave, in a way that a simple obedience-to-Founders-vs.-freedom dichotomy never could have. Obedience, deferring to someone else to make decisions for you, can be appealing even to people who aren't bred for it, and just showing someone what freedom looks like isn't going to make them automatically see it's superior. Forcing Taran'atar into a different state of obedience, an undesirable one, is a more potent and believable way of giving him a true crisis of faith and identity. And it's clearly not over.