What was most important about Albert Speer is that he was the highest ranking member of the Nazi Party to admit to doing wrong and to be very open about what he had done. It is from him that we get a good deal of our understanding of how the Nazi regime worked.
Albert Speer was the Minister of Armaments and War Production for the Nazi regime during much of World War II. In this capacity, he was responsible for making the German economy run as efficiently as possible so that it could produce all of the things needed for the war effort. This meant that Speer was a very important person in the Nazi regime.
After the war, Speer was the only high-ranking Nazi official to express any serious remorse for what had the Nazis had done. There are those who argue that Speer was not completely forthcoming about his involvement in the Holocaust, but Speer clearly admitted to more wrongdoing and expressed more remorse than any other official who held such a high position. This fact is what makes Speer an important historical figure.