Always a relevant XKCD
There is very well know issue with 5 star review systems, better visually discribed as J distribution.
In other words, there is a small spike in extremely negative reviews (★), almost nothing in the middle (★★, ★★★ and ★★★★) and a large spike in positive reviews (★★★★★). This is counter-intuitive, and not ideal — given the option of 5 ratings, one would expect a range of opinions on a given item that don’t cluster to the extremes.
This does not reflect the genral view of audience and is driven by biases.
Therefore a 'Normal' distribution is more preferred, and is inherently natural.
In this project, we try to make a tool bar that automaticaly scores the "Normalness" of reviews.
References:
The Problem of J-Curves (in Online Ratings Systems)
The Problem with 5 Star Rating Methods
http://www.lifewithalacrity.com/2006/08/using_5star_rat.html This paper