Esperanto itself is a small language. But many books on Esperanto over-simplifies Esperanto and in result many books mistake by not giving enough examples or comparative explanations. It's hard to find a good and small Esperanto guidebook. The size is important because you will have to take the guide book with you when you travel overseas. This book is small enough and provides good enough linguistic material (examples, explanations, comparisons). I always travel overseas, with this book in my hands.
For those of you who like languages, Esperanto is for you, and this is the book to make you fluent. This book took me from zero to advanced conversation in the course of just two months! The lessons are well composed and full of examples, and the ease of learning Esperanto has encouraged me to tackle harder languages, backed with the grammatical understanding I have gained from studying Esperanto via this book.
If you want to learn all of Esperanto, all you need is this book and a dictionary. It shows you all the grammar, conversation skills, writing skills, affixes (an important part of the language), plus a fairly complete vocabulary load. It starts out as if you were a complete beginner, and ends as if you were advanced.