First thing first, I'm no native speaker and didn't study English-lit in uni so it's not my place to comment on the language of the book. But I don't think I'm the only one finding it really "conversational" or "youtubal", considering that's where the idea came from.
I am not expecting Sir David Attenborough but the author could at least up the ante by not writing like a scriptwriter for youtube channels. I've seen cosmetic Vloggers write better. And that is not to say he (or she, could be a she) should drop the humour.
The major flaw of this book is its own confusion in the intended audience. It's certainly not suitable for schoolchildren with all the profanities flying in the pages. And it's not for young adults either with its scanty scientific knowledge on the subject of "ferocious small animals" diluted by pictures and tacky jokes.
The notion's quite good. But the author shouldn't have cashed in the trend so hastily without any second thought.