Amazon tends to recommend things I like and the majority of the purchases have been because of their recommendations (good job Amazon, your software is doing it's job, raising sales). I think books and music are different though. Books have well defined categories. If I buy a pop-psych book, say "Blink", and then I am recommended "Peak: Secrets from the New Science of Expertise" it's pretty much going to be very likely I buy that too if I am interested in that subject.
If however I want recommendations for new Metal music, and my previous selection was Metallica then you play me some Megadeth, I am going to hate it and not be interested in it at all!
