I read a comment earlier that made a good point that unlike the console launches of the previous generation in 2004-2006, we now have access to Facebook, Twitter, and YouTube to vocalize and demonstrate our complaints worldwide. It makes the vocal minority much more vocal.
If you clicked on the link above, you will see that nearly 40% of the Amazon reviews are 1*. There is a good chance that most of those people received a dead PS4. Agree that not everybody who received a good PS4 left a positive review but this certainly does not make it looks like a minority.
I would guess that 1/10 would write a review when the PS4 is broken and 1/1000 would write a review regardless.
Also we don't know if these are real reviews or just 323 Microsoft employees who were given money to order the PS4 and then post a bad review :P