Iain M. Banks, Feersum Endjinn, Orbit, 1995.
When I first heard about this book, a certain aspect of it put me off reading it (as I explain below), but I bought it a while ago along with some of the author's other novels, and gave it a chance. It is one of his non-Culture books.
The story is set in a far-future earth, long after a large part of the human population has departed. Humans live eight lives in physical form, after which they have eight incarnations in the Crypt, where human consciousness is stored in a virtual reality. As the story starts, the earth is threatened by a cloud of interstellar dust that is covering the sun, and we follow a few characters in their attempts to prevent the end of life of earth by activating a solution to this problem left behind by the advanced humans who had moved into space.
The aspect of the novel that bothered me when I first read a review of it was that one of the viewpoint characters' stories is written in a sort of phonetic form (hence the title, which is his way of spelling "fearsome engine"). I have always found phonetic writing irritating. Some writers try to portray the regional accents of characters by writing phonetically, and in this case this form of writing is supposed to reflect the character's dyslexia (though I'm not convinced any dyslexic would write like this, and it is not clear why this character would have written down his story, considering how difficult it was for him to write). It just makes the reading experience difficult. I had to adjust to reading these sections, sometimes having to decipher what the words meant. Perhaps this is an attempt to reflect what reading is like for people with dyslexia, but I don't think this experience will increase readers' understanding of dyslexia, or make them more sympathetic.
The story gradually brings together various pieces of evidence explaining what is happening, and follows the characters as they try to make sense of their roles. It seemed to me that the people who prepared for the Encroachment years before and left the mysterious solution could have planned better how it would be activated, preventing the chaos that happened in this story. But perhaps that is actually more realistic, and it creates the threat that drives the plot.
My impression of this book is that even without the annoyance of the phonetic sections, it is far from Banks's best work (which I really enjoy). There are big themes to be considered, the characters develop and change, and the conclusion is reasonably satisfying, if you don't mind a sort of deus ex machina, but for readers unfamiliar with this author, I would recommend starting with some of his other novels.