At just over 400 pages in an abridged form, The Gulag Archipelago took me over a year to finish. The way I took it in, it's a difficult book, and I've probably forgotten more than I currently remember.
Digression: I need to start taking notes as I read, especially with books like this one: academic books, books you're responsible for reading not because they're fulfilling or gratifying, but because they're informing. Informing in either a direct sense, as in the information is scarce and important and a lesson for how to or not to act; or in a derived sense, as in the information shows how other people are thinking about an important topic. Regardless, instead of taking notes and reading thoroughly I end up reading leisurely and out of curiosity instead of duty. It's ineffective and lazy of me. Credit for reading, but no retention. Anyway...
I see The Gulag Archipelago as having three significant characteristics:
The historical content: a high-level account of the Gulag prison system. How it was instantiated, how it was maintained, how it operated, what it produced. Empirical, physical facts about Stalin's Communism.
The psychological content: a low-level account of the people being churned through this political, ideological machine: prisoners, stoolies, guards, orthodox communists, criminals, men, women, children. How it changed people's intentions, how it informed people's decisions and conducted their speech.
The format itself: a certain kind of rhetoric and composition that ends up needing to be deciphered because it's both (a) fragmented, piecemeal and (b) translated Russian.
Number three, the format, is important because this rhetoric can obscure the facts and their effects. At times you get these long-winded poetic analogies in the middle of some description, giving one the impression that if only you were already directly familiar with the Gulag or Mr. Solzhenitsyn's experience before hand, that then these emotional descriptions would be effective and obviously necessary. A catharsis and emotional layer to the undeniable. But so much of the tragedies of communism -- not to mention fascism and the World War Two era in general -- are incredible and fantastic to the peaceful, young, and naive Western middle class of the 2000's (e.g. me). For us, a linear, deep explanation is what, I think, would be effective at imparting a moral and understanding how that moral is achieved as well as how it can be destroyed. Instead, Solzhenitsyn's book can come off as a ramble in its given format. It seems to prefer breadth to depth and anecdote to citation.
That's not to say I don't believe him, or that what he wrote isn't useful or important, or that any of these criticisms, should you agree with me, are inexplicable or the result of a lack of talent or integrity. To be imprisoned in concentration camp for years and to not only retain enough information to write this book but to also to retain the will to write this book is awesome and amazing. Aware of how ridiculously understated this is: I would've been broken by much less, much sooner. What perhaps partially redeems my interpretation is that Solzhenitsyn admits the fault in his post scripts, and credits it to exactly what you'd expect: that he had to recall memories and gather sources created during an ultimate oppression and absolute stress and then write that information down in some kind of legible order years after it occured, all in secret. It's impressive and inspiring and makes you feel like shit for not being even a fraction as honorable.
On to the content, starting with the historical description (what I called Number 1 above).
The most important thing you can learn from this book is that the tragedies of WWII and despots and fascists and communists are not simply explained by pointing to a single socio-path and claiming he had absolute limitless power. Power so intense that no matter how good and plenty the people under him, people who are compelled to do the right thing, were no match for his omnipotent effort towards evil. Instead, you learn the reality of the horror is a much more sophisticated and insidious thing. It's a corruption of the people themselves, the whole of the people, by a combination of an orthodox following of an ideology and a fear to break from the dogma. This combination is then seized on, slowly punishing the dissonents, until all that is left is the orthodox, making what once might've been considered a moderate perspective all of the sudden radical. The new concentration of orthodox is all the more fervent about punishing the radicals, which leads to another new definition of "radical" itself, and concentrates the orthodoxy further. And so the feedback loop continues and intensifies. From this perspective, the totalitarian leader isn't the linchpin of the oppression but rather the catalyst, the spark. A beginning point for a crystallization that spreads like a slow cancer, as opposed to a violet gunshot that does all its damage in an instant.
Guards become desensitized as the work becomes ubiquitous. The work becomes ubiquitous as the opponents to the ideology become more villainous. The opponents become more villainous as the machine squashes more moderates. Else, and else.
Then there's the psychological analysis, observations similar to those made by Victor Frankl in his Man's Search for Meaning. How do people react when all hope is lost? How does despair manifest? How does it galvanize people? How important is freedom? How brave can people be? What kind of cruelty and harshness can people endure? What kind of organization and tribal governance develops when conditions reduce people to animals, and why does it develop? How well can people hold on to their humanity?