I've seen very different opinions, ranging from "greatly exaggerated" to "backbone of the Third Reich".
Also, I'd love a recommendation for a good, academic audio book on the subject.
Thanks.
This question has come up here before in various guises, and there are resources in our FAQ that you might like to review while you wait for fresh responses to your query.
The book most cited in this respect tends to be Goodrick-Clarke's The Occult Roots of Nazism, which is old now, but sensible and highly respected.
Think very much the former of your options.