Picked it up Christmas Eve and finished it late in the evening on Boxing Day (I had plenty of time to read in between several Xmas dinners and family events.)
I really liked the Romulan/Spock portions of the book. Very engaging stuff.
The Sisko parts didn't work as well for me. I felt that several of his actions (e.g. how he left Kassidy) didn't align with his character. He also came off as whiny and more than a bit of a jerk (this element continued through to his command of the Robinson). I also felt that the flashbacks to the earlier Tzenekthi War didn't meld effectively (or at all) with the present-day story.
My major beef with the book is that it is really two books in one --- the Sisko and Spock stories never come together (except for Sisko's meeting with Donatra). This could very easily have been two separate books --- with each story being fleshed out in more detail and receiving more comprehensive treatment.
I rated the book "Above Average" due to the excellent Spock story. The Siskso plot, in my opinion, was Below Average.
There just seems to be something missing from these Typhon Pact books --- like each book just never really comes together in the end...