Yeah, when I read the cover blurb for Saratoga I had the same thought, and sadly after reading it decided I was right. I never cared much for Reunion anyway, I figured out way before the crew did who-dunnit. And when I read Saratoga I thought "Wouldn't it be funny if ... ?" and turned out I was right. Its annoying to read a murder mystery when you figure out the ending long before the characters do, it makes them seem dumb.
The only really good Sisko novel I can think of offhand is the followup to "In the Pale Moonlight" they did a few years back: "Hollow Men"
The real trouble is, the DS9 novels didn't actually start getting good until the DS9 relaunch. Its my favorite TV series, but the tight continuity of the show meant that the novels couldn't really do DS9 justice until they could establish their own continuity free of the confines of the show. And by that time Sisko was "with the prophets." He returned in Unity but then the DS9R kind of fizzled after that.
RBoE is one of the main Sisko-centric stories they've done since then, and yeah, it had mixed reviews. I didn't think it was terrible, but it wasn't great either. Its just a new journey for the character. The Sisko is really not himself right now, he's back in his S1 mindset. I'm confident he'll pull himself out of it eventually.