I found it kind of meh. The Kira section just didn't do a lot for me and I was wondering if it was going to amount to much. It just didn't for me. And the DS9 part was for the most part predictable. While I didn't know specifically Nan was going to die we all knew something bad was going to happen, that was pretty telegraphed. And as far as the initial suspect being cleared, well, who didn't think that was going to happen, we have 4 more books to go after all. But I'm also wondering if the chip in her shoulder was supposed to fail causing confusion during the investigation.
I've only read the first 3 books so far and I liked books 2 and 3 a LOT more than this one. If you look at the the review threads ranking page
you'll see this book ranks well below the rest of The Fall books out so far so that tells me most people feel the lesser book in the series so far.