His collaborator, Hall, recalled:[4] The circle that George Russell would have over to his place included Jimmy Giuffre, Bob Brookmeyer, Gil Evans, Zoot Sims, Bill and others.

Evans biographer Peter Pettinger notes, "There is a hazard attached to combining piano and guitar, both essentially chordal instruments.

"[6] The front cover image for Undercurrent is Toni Frissell's photograph "Weeki Wachee Spring, Florida", which Shadwick describes as "stunning".

In his November 26, 1962, review for DownBeat magazine jazz critic Pete Welding states, "This collaboration between Evans and Hall has resulted in some of the most beautiful, thoroughly ingratiating music it has been my pleasure to hear."

AllMusic critic Scott Yanow notes, "Both Evans and Hall had introspective and harmonically advanced styles along with roots in hard-swinging bebop.

In this sublime meeting, the artists shared a common ground of musical values, Hall confessing to having long been influenced by Evans.

Their equal but differing abilities in caressing a melodic line through gradations of touch and tiny rhythmic displacements keep the listener fascinated at each new unfolding of a song's deeper levels of meaning."