Conversation so far:
Who composed Purple Haze?
Hendrix's techniques "all contributed to the dirty, raw, metallic, [and] angular sounds" heard in the song.
How long did it take to make the song?
CANNOTANSWER.
What are some other things about the composition of the song that are noteworthy?
Biographer David Henderson describes Hendrix's guitar tone as "at the razor edge of distort".
However, individual notes are still clear.

Question: What was so special about the song?
Self-contained rewrite: What was so special about the song Purple Haze?