Just finished GTTS! Overall, some very interesting developments, both character-wise and plot-wise.
One of the biggest positives I felt were the overall interlinking theme of family (including Crusher becoming pregnant which is sure to add some drama down the road). I also felt there were some nice surprises, such as the return and sacrifice of Hugh and formerly unknown Enterprise crew member - Rebekkah (pardon any spelling errors). I thought Geordi was also characterized very well and continues to be sympathetic as a guy who just can't seem to get it right with the girls. I just hope that in future novels, more can be done with individual character development than helping them find/realize their true love (i.e. Picard & Crusher). I was quite caught off guard at first at the huge significance given to Picard's experience in "The Inner Light" and how it had affected his feelings of having his own children. I think I was surprised because although TNG did show us that Picard's experience did remain a part of him (i.e. the flute), it was never really given much further emphasis past that episode. However, it does make total sense that his experience with Kamen's children would affect him as much as had they been his own. So, kudos to a good idea there. Finally, the continuation of the story with the Einstein (now Frankenstein) was a nifty little nugget. I also liked the use of Leybenzon at the end of the story but felt it a little disappointing that his character wasn't able to be redeemed as much as he was portrayed as making a folly of the worst judgement (however, on the other hand, it's good to see when characters aren't always presented in such a predictable/architypical fashion).
Just from speaking with Christopher online and hearing about some elements of some of his other novels I have not gotten around to reading yet, I gained the impression that two big interests/focuses of his are the heavy detail of science (physics in particular) in some elements of the story, and also, experiences with non-humanoid aliens of very different perspectives/natures from our own. Both of these were very noticable in this story. I enjoyed the attention to detail in this regard but did feel that at times very dramatic situations were filled with very meticulous (and possibly unnecessary) explanations of the physics of certain situations. Two examples that spring to mind are the firing of the torpedos into the rift created betwen the Enterprise and Borg Cube (and how they would react) and the nature in which the Enterprise and Liberator attacked the Borg Cube in the pincer-like fashion (I believe it was refered to as) in order to fool the Borg into exposing its injured side. I think that dramatic situations involving physical battles must be difficult enough for an author to write in a nature that keeps it compelling and suspenseful and I found that going into this level of scientific detail on the page detracted from the drama a bit.
My only other negative points (and I only mention them because I always try to weigh in on both the attractors and detractors) would be that I felt the story was quite slow moving at times. I found myself getting a bit bored with the continued encounters with the aliens and attempting to make them understand why we needed to fight the Borg. I suppose it's just a matter of preference that I prefer the alien entities with a bit more similarity to ourselves and whose motivations are more down to earth (e.g. Klingons, Romulans, Ferengi, Organians, Borg, 8472, Vulcans, etc), and I don't quite enjoy as much the ones that have no real connection to real people. The one plus that I felt these aliens really did add to the story though was in allowing for the comments on the nature of children and how they are a part of, and yet separate from their parents.
And as others have mentioned, I'm also beginning to suffer from a bit of Borg fatigue. Three massive Borg threats in the last four novels (as well as one supposedly coming in Destiny) strikes me as a bit much and I find that many of their developments (e.g. killing rather than assimilating, proceeding to attack the Federation out of revenge rather than pure utility) are only serving to make them lose the characteristics that made them unique and are becoming more like the majority of other alien enemies we've encountered. However, this doesn't mean that I'm still not extremely pumped to see what Destiny brings and will probably have to begin reading book 1 tonight.
As for a final summation of GTTS, I think it's an excellent addition to the TNG-R line for it's character developments that are sure to have some lasting impacts.