Comparing the Soviet Union to the Nazis only makes the Nazis look better if you don’t understand the truth about the Soviet Union. Communists are as bad as Nazis, and communist sympathizers and apologists are as bad as Nazi sympathizers and apologists.
And from the review itself:
The Soviet Union’s ethnic murders predated Nazi Germany’s. Stalin was not directly responsible for the Holocaust, but his pact with the Nazis paved the way for Hitler’s killing of Jews in the east.