Well, I just finished TGO twenty minutes ago. For me it was definitely a mixed bag. I thought that Bakker's writing was definitely at its nadir here - even though it's head and shoulders above most fantasy, and as rich with philosophy as always, he didn't manage to evoke the epic feel as well as he has in previous installments IMO. The exceptions there would be Ishterebinth and Akka's parts, with a few more sprinkled in the other threads. To focus first on the negative, I just thought that there was a lot of general... weirdness in Bakker's decisions about where he wanted to go with the series.
There will be rereads in the future to make sense of some of these points, but overall I would say I found these things incongruous:
(wasn't sure where to cut the spoiler so I decided to spoiler everything)
I felt that while there was sufficient in-universe justification for the existence of the nuke at Dagliash, there was startlingly little foreshadowing. It felt like Scott, after waxing on and on and on and on and on for three books about the gibbering tide, needed some kind of expedient way to get rid of it while conserving the grimdark flavor... but there was so much lazy handwaving involved. How did Kellhus figure out the lingering side effects of such an explosion? I can understand deducing it as a powerful Tekne weapon after unearthing it, and I would even go so far as to say I could see Kellhus having studied it beforehand because it seemed like he was very deliberately taking Viri apart to find it... but I felt like there wasn't enough narrative buildup behind it at all. so many other things Bakker could have done to advance this plot that didn't involve so much damn handwaving! Three books of constant descriptions about how, despite constant attrition, the Horde didn't even seem slightly reduced only for it to be wiped away in a few pages and we were left with a few descriptions about there being quite a few bodies, but not more than a few token lines about the scale of the slaughter.
The whole plotline at Momemn was a mess. Again, a whole trilogy of buildup for the Last Cishaurim only for Kellhus to ride in, remark that he was a pretty tough dude, and then overpower him without even a real attempt by Bakker to dramatize their duel. There was so much potential for Meppa, only to have him relegated to a mediocre red herring. At the same time, much like the thread following the Great Ordeal, Kelmomas' POV became rather grating. Like the rest of the Dunyain children, he is a very very thin character, and I almost felt like there was far too much hinting about his association with Ajokli given how little actually happened... not to mention that, despite a couple references earlier in the book, suddenly pulling the natural disaster card only for Kellhus to appear moments later was another example of juvenile storytelling.
So far Kellhus' children have been a real letdown IMO. Inrilatas at least had some interesting hints thrown around about his true nature and the magnitude of his Strength and how it fed his madness, but Thelliopa? Basically meaningless to the overall story. I'm still holding out for Kayutas and Serwa.
Cnauir's reapparance at the end of the book felt like fanservice to me, even if it wasn't. His whole storyline had been very neatly ended in TTT, and while I think Bakker definitely left himself some wiggle room there, he hasn't done much with it so far. I think this, like a lot of my other grievances, are definitely exacerbated by the fact that TUC was cut in half. If all of these things had happened in the middle of a much longer book as opposed to the conclusion of part 1, and we were able to better see their consequences, then they would feel much less arbitrary. Albeit I can't say that I would ever agree with the decision to throw in the nuke or... whatever Bakker thought he had going on in Momemn in TGO. Also, I really disliked the way he used the character of Oinaral Lastborn: he was basically a living plot device that served to convey Sorweel to his father, spewing exposition along the way, then get killed pointlessly to resolve the tension at Ishterebinth.
The Whale Mothers and the rape of Proyas have already been touched upon elsewhere, so I won't even get into it.
That all sounded pretty scathing, but overall I wasn't that disappointed by TGO, going into it knowing that it was inevitably just going to be part 1 of 2. Ishterebinth and most of Akka's arc (albeit almost not at all because of Akka or Mimara themselves) were very satisfying. I also liked a lot of other scenes throughout the book, including many of the ones at Momemn... what little characterization we get of Thelli was quite interesting, and I liked a lot of the scenes where Kelmomas observed the Narindar. I have to say that Esmenet has really been dropping the ball though. I know that she's been starting to question Kel for quite some time now, but finding him covered in blood and filth sitting on a throne after untold weeks of chaos wasn't a massive tell that maybe he's got a little of his dad in him?
I think it's Locke who postulated that we were getting a taste of the real creation myth of Earwa in the Boatman's song and I absolutely agree. One of the strongest points of TGO was how it began to canonize the Hundred's participation in the world. I actually quite liked Psatma and her brief conversation with Kellhus as the voice of the Dread Mother was interesting. I have to say that I think it's also pretty incredible how many of the theories postulated on this site and Westeros in the years since TWLW's release have been proven correct. Kudos to everyone who anticipated the axolotl tanks and (I think Locke again) Kelmomas' affiliation with Ajokli.
Oh, and Emwama as hobbit slave race was brilliant, thank you Bakker for that gem.
Those are my thoughts in a nutshell. tl;dr: TGO was disappointing on its own legs but a decent appetizer before TUC. I think that the only thing I won't be able to forgive unless I see it righted in TUC is that my faith in the grand design of the series has been shaken. Before, so many loose ends seemed like promising attempts to foreshadow or at least imply other aspects of the narrative... but some of the events in this book made me wonder if that's really true or if I've fabricated a lot of that greater meaning, and the series is more one-dimensional than I expected.