In Night, what was Elie Wiesel's first impression of Auschwitz after leaving Birkenau?

Eliezer's first impression of Auschwitz was that it was better than Birkenau.
Witnessing the massive amount of killing in Birkenau was Eliezer's introduction to the horrors of the Holocaust.  He experienced personal trauma because it was the last time he saw his mother and sister.  They were sent to a different line than Eliezer and his father.  He also saw the extent of the Nazi death machinery.  Eliezer recalls the faces of the children he saw enter the crematorium, and the vastness of suffering surrounding him: "This is what the antechamber of hell must look like. So many crazed men, so much shouting, so much brutality."  
Eliezer suggests that the prisoners "had already lived through a lot that night" and that "nothing could frighten us anymore."   As a result, Eliezer's first impressions of Auschwitz was that it was better than Birkenau.  He explains how the buildings were made of concrete, an improvement from Birkenau's wooden barracks.   Additionally, Auschwitz is the first place where Eliezer experienced being treated as a person.  As the prisoners enter their block, the Polish man in charge addresses them.  Eliezer describes him as smiling as he speaks about what the prisoners will experience.  Eliezer notes how he wished them a "good night" as they slept.  Such a gesture carried tremendous importance given what Eliezer had seen and experienced in Birkenau.