An internet community of musicians that I frequent collectively played with Hit Song Science during their "free trial" period. Basically, we discovered that it

An internet community of musicians that I frequent collectively played with Hit Song Science during their "free trial" period. Basically, we discovered that it doesn't do a very good job. For example, I had a track that was 1:57 long with a very slow tempo and a minimal arrangement, however there was a slide guitar towards the end. This gave it a really high affinity with a bunch of US chart-topping country & western hits, and so it had a score of something like 8, which is just absurd. So while I like the general principle, we discovered very quickly that its "similarity" metric is probably just too simple. There seemed to be a very weak correlation between songs that we thought sounded like hits, and the score they got on HSS.