Absolutely essential. I love this set, second only to the Village Vanguard recordings, for me. Lots of repetition of titles, but of course never the same way twice! Plus there are versions of Afro-Blue, Blue Trane, and Mr PC. The sound is uneven and there are discographical errors in the booklet (detailed on David Wild's site), but the quality of the playing is worth it. Wonderful music from the early 60s period of Coltrane's quartet- if only there were more live releases from this period!