I enjoyed the first two books in the Lords of Creation series and even reread them fairly recently. As homages to golden-era sci-fi they stood up well while being liberally sprinkled with the Stirling Special Sauce of great characters, "what-if" world-building, and good plotting.
So I was excited when I saw a final book in the series had been released.
Unfortunately, it was seriously disappointing.
* The setting was too big. (Yes, I know that was part of the point. It was still too big.)
* The primary characters were all "check-markers" - female, bi-, Mary-Sues
* The obligatory native lover subplots were predictable, repetitive, and boring, with both lovers woefully undeveloped
* The "can we trust each-other long enough to work together and save our skins but still maintain appropriate distrust and suspicion because we know we're all spies for our respective cold-warring governments" sub-plot between the two female leads was never well developed
* The plot floundered early on when the primaries got stranded with a not-super-interesting group of natives and embroiled in a who-cares power struggle while waiting for rescue. It then hopped around wildly with so little time spent developing any of it that I couldn't even begin to get involved
* The end, when it came, was sudden and unsatisfactory, with a near-insulting level of "pretty little bow"-tying.
Stirling is, at his best, an amazing writing with a surprisingly complex grasp of human nature, history, technology and religion. The first three "Emberverse" books and the parallel "Island in the Sea of Time" books are, while not perfect, classics of their genre, full of imagination, well drawn characters, and fascinating plots. As mentioned, the first two Lords of Creation books where pretty good too.
But this is not Stirling at his best. This felt like a phoned-in, contractually obligated series entry with no heart.