Cold. Very cold. And as a reader, you are visiting a prison camp in Siberia for only one day. A lifetime or multi-year sentence is hard to process.
Shukhov (Ivan) has been sentenced to a labor camp in Siberia under Stalinist rule. It's a cold, brutal and dark existence. He's a practical man and doesn't spend a lot of time wishing for his past life or family. It is this practical and methodical personality that has allowed him to survive for so long in such tough conditions.
There is a definite social structure in his camp and favors (cigarettes/food) can be bartered for by being smart with relationships. The guards assigned to the camp feel as if they are tired of being there as well and are under the same punishment as the prisoners they are there to watch.
This is a slow read; many small things happen in very few words. Each action and situation is composed of many layers. Is the bread given out to be eaten or saved for a later time? If it is saved, where to keep it so that it isn't stolen? Is it shared, could it be used later for bartering for another better prize? Each day is filled with decisions that impact survival.
It's an uncomfortable book both physically and mentally.