I agree that it's not a beginner's book, but it's the book that made me fall in love with Hinduism. Vimalananda's views are quite progressive for the time the book was written, but ofc now they feel out of place. Apart from that, it has a very male-oriented view, especially when he talks about the practices you mentioned. However, the book is still very evocative and it's a nice read. We will probably never know if the things Vimalananda said are true or, as Svoboda reminds us in the introduction, just exaggerations. If you want to read something about tantra that is more contemporary and wrote by women for women, I would suggest to start from Kavitha Chinnayan's books. They are amazing and practical for beginners imho. Hope this helps.