I sorta agree, but I also think one of the reasons that the first part is stronger has something to do with the protagonist’s age. When she’s just an innocent little girl, you feel incredible tension every time she is threatened. As she gets older and more capable, the danger doesn’t connect as viscerally to the reader (in my case anyway).
But, warts and all, still one of my favorite novels ever.
Agree it's inevitable that it loses some tension and sweetness (and the role of the all-important Primer), but it's more that Stephenson just takes her in terrible directions (she decides to work in a brothel dictating BDSM fantasies, then she gets violated by rebels, then she unironically becomes the Victorian colonialist ideal of the great White Leader the Chinese girls need) and the others in even worse directions (disappear from the narrative, die a pathos-free death, wake up after 12 years of drug induced orgies and have no emotional reaction whatsoever but a compelling need to wander into a pace-killing subplot about a theatre). The plotting is clunky, I'm not sure the writing is as good despite a few nice moments and the whole Drummers orgy-computer concept is best reserved for another book, preferably unpublished.
Hmmm. Tequila (Nell's mother) vanishes which is weird (it's plot necessary, but in reading and re-reading I don't think she's even firmly written out, she just vanishes)
But the other recipients of the Primer both do something it's just that this novel isn't about them, indeed maybe the point is that their paths diverge so enormously. Princess Nell is exactly what Nell intended from the get go. We don't see Elizabeth and Fiona's first interactions with the Primer, it seems safe to assume they do not begin by escaping from a terrible castle since their lives are comfortable and there's nothing to escape from.
To the reader perhaps it seems like Fiona doesn't amount to anything, but we're not shown very much about it, and it may well be that to her this is every bit as much what she wanted out of life as Princess Nell's outcome. All we know about Elizabeth is that she joins CryptNet. The novel never even tells us (beyond hints) what CryptNet is about. It tells us what CryptNet claims to be doing, and it tells us that nobody believes that.
You could read it as the other two girls fail, but I'd argue that from what Elizabeth's grandfather says at the start, and what the Constable tells Nell later, we can see that the grown-ups have a sense that actually conforming to somebody else's expectations is exactly what they don't see as a path to success. All the parents want what parents so often want - younger copies of themselves, but that's stupid. Nell isn't what Tequila (or Bud) wanted, Fiona isn't what Hackworth wanted, and Elizabeth plainly isn't what her mother and father seem determined to make of her, which suits her grandfather down to the ground.
I get the point that they're not conforming to expectations, which is fine, but having set them up to be observed failing to conform to expectations, we get an "It's ten years later now. Elizabeth's disappeared to join mysterious hackers. Fiona's had no father for a decade but we won't dwell on that, here's a novella about a night out at Dramatic Personae instead. Oh, and Nell's brother who was super important at the beginning died too, poor him. And Nell's ignored the the messages about empowerment and science education messages but been inspired by all the racting to checks notes make up kinks for middle aged men, and we're not even going to riff on the clash with the values of the 'Victorian' middle class upbringing she was donated that implies"
More to this point, you could imagine 2 alternative versions of the Diamond Age, exploring the same world, but from the eyes of each of Fiona and Elizabeth. Nell's story isn't necessarily more interesting, and her outcome wasn't necessarily more successful: She's the one of the 3 the book focused on.
Cryptnet and Dramatis Personae were both intriguing, mysterious organizations that were written to imply there's much beneath their surfaces the plot only touched.
Yeah, I think the dissonance I fundamentally had with the ending of The Diamond Age is that it seems to not have any sense of irony (or any concept that, maybe, the Seed might not be the awful idea that his protagonists are trying to sell us that it is, for example).
But, warts and all, still one of my favorite novels ever.