This is absolutely fine jazz, and this may not be fair, but all the time I listened to the CD I made a kind of reference to the CD "Getz meets Mulligan in HiFi", which has more substance and drive, maybe because of Oscar Peterson's piano and Ray Brown's bass.
On the Desmond/Mulligan CD I sometimes gets the impression that the rhythm section are doing their stuff, and the saxophonists are doing theirs, and that it doesn't really jive.
I have still given the CD 4*, because of their fine chamber jazz performance.