How useful are Amazon reviews?

Just like you dear reader I like to think of myself as a pretty thorough type of guy. So when I buy something on Amazon that I don't really have much knowledge about I tend to check the reviews to make sure I'm not buying, well, a bag of shite. So here I was looking at a small media player to plug into my TV and noticed one five start review entitled 'great' which read 'the product is what i wanted it fits well it looks even great its a very good product highly recomend'. Sounds good I suppose and I'm happy to excuse the poor English. But on closer investigation I noticed that the reviewer had actually posted a total of 63 five start reviews, all for different products, and all called 'great' and with the same glowing appraisal. Actually one of them was called 'woeeeeeeeeeee' and had slightly different wording. So I did the decent thing and reported the reviews to Amazon on the basis that there was a trend there which implied they weren't necessarily helpful for anyone really. So maybe in future I'll treat Amazon reviews that same way I treat Trip Advisor ones - ignore the five star and one star reviews and just believe the ones in the middle.