Relies almost entirely on personal stories from readers, and it clearly seems written with an agenda in mind. I wouldn't recommend it to parents as the best way to support their children- it has a rather 'interesting' interpretation of factual evidence from credible sources.
Abigail & several of her readers have also used the photos and faces of several notable transgender men to promote their work, without their consent or knowledge. With that in mind, I really think Abigail set out to prove her point, not to help parents of children suffering from gender dysphoria.
For parents looking to find resources that will help them connect with their child and understand their experience, I would recommend Pride and Joy by Rachel and Sarah Hagger-Holt and Helping Your Transgender Teen by Irwin Krieger.