The only way any Star Trek novel can possibly be enjoyed is to read everything that came before, starting with the Bantam series from the 70s and then reading all the Pocket novels in publication order, except for Triangle, which should be read every 3 months just to savor it. Also, if you lose track of what happened back in #57, for example, I suggest you read it twice. Otherwise Destiny or Q&A just don't make sense, dammit!!!1!
I used to think this kind of post was an exagerration, but after trying to read Destiny 1 before Greater Than the Sum, I'm not so sure.
I remember an entire chapter focusing on some character that (I guess) was introduced in GTtS. The author gives absolutely no indication of who this character is or why he's in the scene. After that, he just vanishes from the rest of the book leaving the reader thinking "WTF mate?". I wonder how many more such moments there would have been if I hadn't followed Titan and the DS9 relaunch. I know without the DS9 relaunch, "Captain Ezri Dax" would be a big WTF moment.
I have no idea what the hell you're talking about. I just skimmed through the first five chapters and prologue, and almost every single POV character reappears later throughout the book (and has their backgrounds explained in the text): Ezri Dax, Sam Bowers, the Unknown Alien Entity Aboard Columbia, Erika Hernandez, Christine Vale, Xin Ra-Havreii, Deanna Troi, Will Riker, Jean-Luc Picard, Worf, and Lonnoc Kedair.
The exceptions are Jadzia Dax (who of course died during DS9 after the prologue was set), and Celia Komer and Yott, whose disappearance from the rest of the novel is explained by virtue of their being killed.