I greatly enjoyed metropolitan man, but feel like web serials, especially fan fiction, are their own genre and deserve their own post.

The Gap Cycle by Stephen R. Donaldson

I think I've read this twice, in my early teens and early twenties, and loved it both times. But I'm now 34 and can't talk about it in depth. I think past-me especially liked the grimness and was impressed at how characters seemed to be doing things for internally motivated reasons. (IIRC Donaldson calls this giving characters "dignity". I feel like since then I've picked up another term for it that's temporarily slipped my mind.)

I still think A Dark and Hungry God Arises and This Day All Gods Die are excellent book titles.

A caveat is that back then I also loved Donaldson's Thomas Covenant books, and I think that by my mid-twenties I enjoyed them but not so much. So plausibly I'd like the Gap Cycle less now than then too? But I want to re-read.

Too Like the Lightning by Ada Palmer

I once saw a conversation that went something like: "I don't find writing quality in sci-fi that important." / "You clearly haven't read Too Like the Lightning".

I wasn't sure if the second person meant TLTL's writing is good or bad. Having read TLTL, both interpretations seemed plausible. (They meant good.)

I found it very difficult to get through this book, except that the last few chapters were kind of gripping. That was enough to get me to read the next one, which was hard to get through again. Ultimately I read the whole series, and I'm not sure how much I enjoyed the process of reading it. But they're some of my favorite books to have read, and I can imagine myself re-reading them.

Crystal trilogy by Max Harms

I enjoyed this but don't have much to say. As an AI safety parable it seemed plausible enough; I hadn't previously seen aliens like that; I occasionally thought some of the writing was amateurish in a way I couldn't put my finger on, but that wasn't a big deal.

Imperial Radch series by Ann Leckie

Very well-crafted world. Some might dislike the robotic narrator, some might enjoy it as a fun layer in a complex plot puzzle. High scifiosity.

Southern Reach trilogy by Jeff VanderMeer

Surreal & unusual novels. Good tone & imagery. Unlike Radch, i think this is more about style & perspective than a style layer over a intricate, hidden plot layer.

Too Like the Lightning by Ada Palmer

I read a lot of scifi, but i haven't gotten this obsessed with a book since Green Mars! Like Radch, a unreliable narrator presents a intricate world. Set on Earth four centuries in the future, it follows the political, technological, & dialectic trajectories of a culture that has mutated in strange & fascinating ways from today. Try it for the economics of future aircraft & the vivid soliloquies. Avoid it if you dislike books that frontload worldbuilding & characters, where the plot is confusing until the end. I love it & i have another post about it here.

This is How You Lose the Time War by Amal El-Mohtar & Max Gladstone

I found this short book very fun & cool. About spies in a extraordinarily spectacular time-travel war. Does feature some very confusing plot points that i still don't understand.

XX by Rian Hughes

Recommended, but only the print version. It is absolutely pointless to read it as an ebook—don’t even try. But as a print book it’s really something.

Imperial Radch series by Ann Leckie

Outstanding series. Strongly recommended. Classic space opera, philosophical exploration of identity and personhood, excellently written. Some of the best sf I’ve read in a long time.

A Memory Called Empire by Arkady Martine

More good old-fashioned space opera. Not quite as satisfying as the previous, but beautifully written. Also recommended.

Silo series by Hugh Howey

I enjoyed several books of this. I think it keeps going? But I have no intention of finding out. I read just enough of this series to have been satisfied with how much of it I have read.

Too Like the Lightning by Ada Palmer

I absolutely could not stand this book. It seemed like it was written specifically to annoy and disgust the reader. Mission successful, if so—I didn’t even get a quarter of the way through it.

David’s Sling by Marc Stiegler

Mostly of historical interest (it’s mentioned in the Sequences, and it’s somewhat interesting to see what sorts of things people were envisioning, back then, as hoped-for outcomes of successfully developing and spread rationality techniques). Readable enough, but not exceptional, otherwise.

Might be worth posting this as it's own question for greater visibility

re: The Fractal Prince (really the whole Quantum Thief trilogy), I may be biased, but when I first read it I had 2 reactions: (1) this is the most targeted-at-my-ingroup novel I have ever read (2) nobody outside of my ingroup will get the kajillion references flying around, since Hannu Rajaniemi never bothered footnoting / defending any of them (unlike say what Peter Watts did with Blindsight), so people will think he's just making up technobabble when he's not, which means he'll be generally underappreciated despite the effusive praise (which will be of the generic "he's so smart" variety), which made my heart sink. 

But Gwern not only got it (unsurprisingly), he articulated it better than I ever could, so thanks Gwern:

Hannu makes no concessions to the casual reader, as he mainlines straight into his veins the pre-deep-learning 2010-era transhumanist zeitgeist via Silicon Valley—if it was ever discussed in a late-night bull session after a Singularity University conference, it might pop up here. Hannu stuffs the novels with blink-and-you’ll-miss-it ideas on the level of Olaf Stapeldon. A conventional Verne gun is too easy a way of getting to space—how about beating Project Orion by instead using a nuclear space gun (since emulated brains don’t care about high g acceleration)? Or for example, the All-Defector reveals that, since other universes could be rewriting their rules to expand at maximum speed, erasing other universes before they know it, he plans to rewrite our universe’s rule to do so first (ie. he will defect at the multiversal level against all other universes); whereas beginner-level SF like The Three Body Problem would dilate on this for half a book, Hannu’s grand reveal gets all of 2 paragraphs before crashing into the eucatastrophic ending.

For world-building, he drops neologisms left and right, and hard ones at that—few enough American readers will be familiar with the starting premise of “Arsène Lupin in spaaaace!” (probably more are familiar with the anime Lupin The Third these days), but his expectations go far beyond that: the ideal reader of the trilogy is not merely one familiar with the Prisoner’s Dilemma but also with the bizarre zero-determinant PD strategies discovered ~2008, and not just with such basic physics as quantum entanglement or applications like quantum dots, but exotic applications to quantum auctions & game theory (including Prisoner’s Dilemma) & pseudo-telepathy (yes, those are things), and it would definitely be helpful if that reader happened to also be familiar with Eliezer Yudkowsky’s c. 2000s writings on “Coherent Extrapolated Volition”, with a dash of Nikolai Fyodorovich Fyodorov’s Russian Cosmism for seasoning (although only a dash²⁾.

This leads to an irony: I noted while reading Masamune Shirow’s Ghost in the Shell cyberpunk manga that almost everything technical in the GitS manga turned out to be nonsense despite Shirow’s pretensions to in-depth research & meticulous attention to detail; while in QT, most technical things sound like cyberpunk nonsense and Hannu doesn’t insert any editorial notes like Shirow does to defend them, but are actually real and just so arcane you haven’t heard of them.

For example, some readers accuse Hannu of relying on FTL communication via quantum entanglement, which is bad physics; but Hannu does not! If they had read more closely (similar to the standard reader failure to understand the physics of “Story of Your Life”), they would have noticed that at no point is there communication faster-than-light, only coordination faster-than-light—‘spooky action at a distance’. He is instead employing advanced forms of quantum entanglement which enable things like secret auctions or for coordinated strategies of game-playing (quantum coordination, like treating the particle measurements as flipping a coin and one person does the ‘Heads’ strategy and the other person does the ‘Tails’ strategy does not require communication, obviously, but surprisingly, quantum coordination can be superior to all apparently-equivalent communication-free classical strategies). He explains briefly that the zoku use quantum entanglement in these ways, but a reader could easily miss that, given all the other things they are trying to understand and how common ‘quantum woo’ is.⁠^3⁠ 

Rajaniemi confirmed that Gwern "got it" like nobody else did:

As a longtime fan of gwern 's work -- gwern.net is the best rabbit hole on the Internet -- it's a treat to see this incredibly thoughtful (and slightly spoilery) review of the Quantum Thief trilogy. gwern.net/review/book#quantu… Gwern perfectly nails the emotional core of the trilogy and, true to form, spots a number of easter eggs I thought no one would ever find. This may be my favorite review of all time.

I admire Rajaniemi for pulling it off as you said, but I'm somehow not that surprised. He's bright (mathematical physics PhD) and has been working at writing-as-craft for a while:

But talking to him about his rapid career, it’s quickly apparent he’s no stranger to being compared to other sci-fi rising stars, having first seriously begun writing in 2002 while studying his PhD as part of writing group called Writers Bloc – which includes authors Charles Stross and Alan Campbell. “It is, and always has been a place with quite a harsh level of criticism,” he says. “But in a healthy and professional way, of course, so it was a good group of people and environment in which to develop.”

I personally got the Quantum Thief trilogy because I'd been blown away by Stross' Accelerando, wanted more, and saw Stross say of Rajaniemi: "Hard to admit, but I think he’s better at this stuff than I am.  The best first SF novel I’ve read in many years." 

The two other books in the series (particularly The Dark Forest)

I found the series to be a slog until about halfway through The Dark Forest, when jura Yhb Wv ragrerq pelbfgnfvf naq jbxr hc gjb uhaqerq lrnef yngre. After that, the series ramped up, and I couldn't stop reading.

It's a prequel in the loosest possible sense. In theory they could be set in two different universes and it wouldn't make much of a difference.

You're O.K. to read in publication order.

I read A Deepness in the Sky first, and haven't yet gotten around to A Fire Upon the Deep, and I enjoyed the former quite a lot.

Possibly, but some of the missteps just feel too big to ignore. Like what on earth is going on in the second half of the book?

I thought the sequels were far better than the first book. But I have seen people with the opposite opinion.

Oh (not a spoiler) the second narrator is obviously not being entirely truthful.

That's totally a spoiler :-), but for me it was one of the most brilliant twists in the book. You have this stuff that feels like the author is doing really poor sci-fi, and then it's revealed that the author is perfectly aware of that and is making a point about translation.