I just finished Volume 2. It should be required reading in all high schools, as I heard it is in Russia currently.

I laughed a few times. Both from the author's humour and from the absolutely absurd incidents Solzhenitsyn recounts about certain situations. It's a very interesting read. You'll learn a lot about how Soviet citizens lived, Soviet ideology, how gulags were like of course. The books will make you appreciate the horror of what happened. I knew it was bad before reading these books. You can't imagine how bad it was. Gotta read it.