It is also the most free eyeballs your product is ever going to get. Start off with an intro paragraph like "Our new widget, available now on Amazon, is the easiest way to toast bread in the morning without starting a kitchen fire! If you like toast..."

Also helps to put the rest of your rant in context. I know nothing about guitars, so I immediately think someone's kid who knows how to play is more qualified than I am to say your product sucks. Why not?