JASON SNELL, MACWORLD:
" ... the truth is that product reviews have always been personal, biased, and idiosyncratic. Scoring systems are made by people with their own opinions about what aspects of a product are more or less important. Reviewers bring their own usage history to the party. In those days, we cloaked all of that behind a veil of utter impartiality, but of course all our biases were baked in."
This is a good look at product reviews and its reviewers. Read it, here.
Also, read Brian X. Chen's opinion piece that prompted Jason Snell to write about it, on measuring the value of how companies treat customers who rely on product reviews when making buying decisions, here.