Pretty good! I tried it with some random cross-genre combinations of stuff I like and it found a bunch of other fairly niche bands I like. Looking forward to trying out the other recommendations. Works fine for genres other than punk & metal btw.
Blog post below on how the hate5six creator made this algorithm. Boils down to using the lyrics and community listening habits from last.fm to build a similarity graph for artists, then community detection to group similar artists.