I have observed some trends with reviews that baffle me. Lets look at the different review trends that you might see.

This is what you would call a normal curve in the world of reviews.
Mostly positive, gradually degrading to
the negative. the preponderance of 5 stars and 4 stars will make the reader take a probability call on whether she should buy the book or not.

This is a slightly erratic chart. hugely popular product, but with a sizeable number of distractors. You would notice here that the 1-star is higher than the 4-stars. There is still a good probability that you would like this book, but a good chance that you might be in the category of 1 star folks. You would still go for it.

This chart would be very misleading. Very few folks in the middle and a high number on either sides. Very risky proposition. Typical for a book where the author has taken a stand for which people have taken sides.
The review is not based on the merit of the product. People either like it or they dont based on some prejudice they have.

These are the kind of reviews that we all love.. isnt it. No doubt in anybody's mind that this is the product we should buy. Kudos to the maker. Lets go with what everybody is saying and buy this product!