Highly informative and funny, What's the T? excels at delivering information in a easy to consume way, the illustrations alongside were so helpful and cracked me up. I read This Book is Gay, and absolutely adored that and knew I had to read this one as well. This primarily follows Trans and Non-Binary experiences. I will say I do feel like this book was majorly focused on all things related to being Trans, and while it had a ton of great information, stories, and resources, it felt like it fell a bit short regarding the Non-Binary experience. Though I do feel like it is difficult to fully cover any subject or topic where everyone has such a deeply personal and different experience regarding their gender identity. My favorite parts of the book included snippets of other people's experiences, and what they have gone through. I also really like how Dawson addressed some of the issues around This Book is Gay, primarily related to race and such. 
I recommend this book for anyone who is curious, questioning, or just wanting to educate themselves a bit more.