When you evaluate a book it is not from justice to say that it contains, for example, fabricated or weak hadeeths, or eccentric opinions, mentioning only its dark aspect and neglecting its other positive aspect, which contains interesting beneficial instructions, or scholarly research. Surely, by mentioning half of the truth and disregarding the other half, you are not being just. For many, as soon as they see a mistake in a certain book they avoid it all together and warn against it just because it contains a weak hadeeth or a mistake concerning an issue. If we treat the people of knowledge accordingly then we won't have any more books. We should not mention defects in book, without mentioning its advantages if it has any. From Islaam.com