In this book Daniel Tammet deals with a lot of topics that interest me as well: Math, Mind, Language, Creativity - he presents a lot of information that is quite interesting - especially his first-person views of synesthesia and of perceiving numbers semantically (i.e., the number theoretical properties like divisibility to his mind resemble grammar/morphology of sentences/words).
The facts are quite up to date, most things will be known to people interested in these fields, though.
I find myself agreeing with some of the goodreads commenter, that the style has a strange flatness to it, which I initially would have put down to reading it in translation, but it seems also to apply to the English version.
Found him a bit too harsh on Sacks, too... but I can understand his reasons.
Overall, a good book, you can read a lot worse on the subject(s).
Afterthought: I think, I may take back my verdict on flatness; I am not totally sure if I can justify ...
I liked his insistence on the importance of humanity (i.e., the esssence of being human), even though I don't share his rejection of even mild transhumanism - to me, e.g., gadgets serve efficiently as "brain extensions" up to the point, where I physically feel the effect if I lose my "external memories", i.e., I think humankind can incorporate (bio)technology into its culture without fear, in the same way as it has incorporated books at the cost of oral traditions. Somehow I think his view is understandable, as these "analog" abilities of the mind define him very much.
Another thing, I want to add: this sounds trite, even harsh, but *everyone* is essentially misunderstood and met with preconceptions, savants make no exception ...