Bad Review
One bad review and you think the book is discredited? Come, how many times have you been to the movies and seen something that you liked which received at least one poor review? A review is just a personal opinion. Read the book and make up your own mind.
The guy who wrote the review is obviously biased towards the Christian religion. Anything he disagrees with, he states has been discredited, without providing evidence. Mithraism, for example. It is obvious that Christianity has borrowed from Mithraism, the similarities are too striking not to be real. Yet the guy who wrote the review ignores this fact.
Try finding a review from a secular source and see what it says. Try reading an objective opinion written by someone who does not have a vested interest in disputing the contents of the book.
As Ted Hendleberg said, "The only people who fear non-Christian literature are Christians."