This was a much more enjoyable read then the last book, foundation's edge. We are back to almost reliable narrators and character development.
Overall, a decent read and a reasonable twist.
This book clocks in at 500 pages, which I think is over-generous - large chunks could have been streamlined out without loss of plot or character development.
unreliable patterns
Following the established pattern of the last three books, about 3/4 of the way through the book all the main characters make some horribly out of character choice (like brining the mule around, the fallom teenager around everywhere) and it sticks out like a sore thumb... And just like the last 3 books it's revealed in the last few pages everyone was being controlled from afar against their better judgement..
I found the entire teenager Fallom tangent insufferable, much like the Mule character.... in lore they have a super fast magic ship that can go anywhere quickly... why not drop off their rescue at Gaia and be done with it... why lug them around... there is no urgency here. it just doesn't make sense.
We never get a satisfactory in-lore reason why our Captain has magic decision making powers that are always ethnically pure.
The wizard of oz has been a positronic robotic for 20,000 years... a robot who can control people's minds through hyperspace... This is the third time this EXACT plot has been used in 5 books... at some point we are going to run out of curtains for the real power to hid behind.
Laws of robotics and agency... harm to human's doesn't include loss of agency in this context (take over teenager's mind, reprogram people at a distance, force everyone into a hive mind). The galaxy brain envisioned is no different then the Matrix, or just straight up lobotomizing everyone... humans will stop evolving and exerting any free will, and that doesn't violate the laws of robotics....
Not to mention the previous laws won't exist in the Fallom/Custodian merged mind, so no more limiters... it's assuming the new entity will be a benevolent galaxy despot... Do you want a Warhammer universe, because this is how you get a Warhammer universe.
I really would have liked to see some discussion of free will, evolution, limitations of hive minds being explored rather then just accepted as gospel (but... magic unreliable narrators)... imagine if the Borg had a good PR agency.
20,000 years is 1,000 generations... humans should be diverging on 20 million planets at this point, even if there are not aliens yet, the humans themselves are becoming them.