One would think that the novel would improve once it hits the actual plot, but sadly this isn’t the case. The main reason for that is that the overall theme of family and children is totally oppressing any kind of flow that the story could have otherwise. You want to have an overall theme carried through the whole novel? Fine, no problem with that, but do it with subtlety and don’t slap it over everything in the novel. Here, it's totally pushing the actual Borg plot into the background and is nothing but annoying in the end.
I think you've misconstrued the purpose of the book. The Borg were not the "actual" plot of the novel. They were the McGuffin. We'd already had two novels centering on the Borg and were about to have a trilogy driven by them, so I was going for a change of pace, a more character-driven and exploration-driven tale. The hunt for the Einstein
was just the means to set the character and exploration storylines in motion.
I think I've used the wrong word when I wrote "plot", I actually meant the "event" of the novel (as in what is physically happening in the novel beside the recapping and character stuff). I like character stuff, too, but, unless it is a short story, only in a healthy mix with "action" (not in the the fights and deaths sense, but in the sense that something is actually happening), and for me in GttS the character stuff was just overshadowing everything too much.
Don't sweat over it. Every author has at least one "Get out of jail" card with me, just make sure I like your Titan book more and everything is fine.