Gods of the Ancient Northmen

This is not a book to read if you want an overview of Germanic religion. It is an academic text written for specialists, and is very difficult to follow if you do not have knowledge in various cultures religious domains. I do not, so it was a struggle and the section on Heimdall feels quite speculative at the end of the book, but that's okay because the author acknowledges that there is virtually no evidence of his existence and Germanic mythology, implying that he will be speculating.

Still, if you read it casually, you will walk away with a basic, tenuous knowledge and understanding of Germanic as well as indo-aryan, and Celtic mythologies. It might inspire you to read more layman friendly books, or maybe even the Icelandic sagas. But you probably will not learn a lot from reading this book unless you already have an understanding of the material via some introductory course.

If you are not looking for a real intellectual challenge, I would steer clear of this book and look for something written more for a lay audience. My understanding is that Neil gaiman has done this for Norse mythology, but I've not read his book.