It's an interesting book. It uses a short terse style, like a Russian Hemingway, which is the way to write about these things. The book is meant to record an absolutely typical day in a soviet gulag and show the indominatability of the human spirit, amongst suffering, inhumanity and tyranny. It does a reasonably good job of that and I get Solzhenitsyn's point, but its still quite inferior to something like Darkness at Noon in my opinion.
I liked it, but did not love it. I'm not convinced that showing an absolutely typical day is the best way to go around this project. If we compare it to Fatelessness by Kertesz, I think that did a much more effective job with the Death Camps than this does with the Gulag.
Slightly overrated, but worth reading.