Just finished reading this a few moments ago. With respect to David Mack, this may be my favorite of the Typhon Pact books so far. I'm biased, of course, being a Sisko fan (and a Niner).
As hard as it was to read Sisko being put through an emotional meatgrinder here, the tension with Kasidy was perfectly understandable. As a Maquis, I imagine she bears some ill will toward Starfleet, and few civilian mothers would prefer the risky life aboard a starship to the safety of Bajor. I suspect this, rather than Sisko's superstitious belief that his decision caused Vaughn's ruin and his dad's death, is what the Prophets were referring to. Sisko has seemed more a Legend than a man in the DS9 relaunch books: the venerated Captain, spoken of in the past tense because he's off in subspace. His reappearance at a pivotal moment in Unity only boosted that legendary aura, and in the Worlds of Deep Space Nine -- Bajor book he felt like a saint, above the cares of the world. This book brings him down to Earth again: he's back to being a human, back to struggling with issues and making hard decisions. It's wrenching to see what he goes through (and some of the choices he makes!), but I look forward to seeing him as he tries to sort out his place in the new universe.
I probably would have read this in one setting, but I prefer to only read one Trek book a week, and so I stopped myself last week from finishing this. Fortunately DRGIII put a nice, convienent Part 2 divider in there. I never had to force myself to read...in fact, it constantly tempted me every time I saw it, and once I started I didn't particularly want to stop. The only other book I've read by this author has been Provenance of Shadows, which I also enjoyed, but not as much as this. I'll have to add him to my ever-lengthening list of Trek authors whose upcoming releases I wait for.