I've tried them and they were hit and miss, also to make things more niche most of my music is a mix of video game music and film/anime music, which Spotify is quite short on.

Spotify and other services are trying to make you discover new music. While that's useful I just want it to analyse my local music and work out what to play.

Its a shame the tech exists but as its patented (I think) you can't simply make an open source version, I believe really it's just a 2d graph plot against tempo and some other metric derived from analysis.