The music alone on this album makes it significant, especially since the mangling of the tracks through both the editing and the mastering process have been undone. More about that below.
While this CD version's product page does not have sound samples at the time of this review, the MP3 version's product page does at Underground. Listen to those because they will reveal more about this album than a few thousand words.
I mentioned editing and mastering issues. When this album was first released in 1968 tracks two and six each had approximately four minutes edited out. Most of the editing on those tracks focused on cutting out Larry Gales' bass and Ben Riley's drum solos. Normally those would not be a loss to anyone but bassists and drummers, but they did set up phrases that followed and without those segments the character of the tracks were changed.
Worse, the tracks were subjected to some of what I call 'slash and burn' editing. Post production played with compression and equalization, and added effects like echo. For the era that was a fairly accepted approach, but it also wrecked the original album in many respects. This album has been remastered - correctly - from the original, unaltered tapes and the sound difference is astonishing.
The musicians are Monk on piano, Charlie Rouse on half the tracks (2, 4, 6, 8 and 9), Larry Gales on bass and Ben Riley on drums. Vocalist Jon Hendricks was a drop-in guest in the studio that Monk talked into improvising on track 7. I personally love it and you can hear the vocals in the sound samples.
It's interesting that this album took a year to the day to complete. The first session was on December 14, 1967 (track 2 and track 8's alternate take) and wrapped up on December 14, 1968 (track 6). Both takes of Boo Boo's birthday were recorded on December 21, 1967 and the remaining tracks were recorded on February 14, 1968.