[1] Editors at AllMusic rated this album 4 out of 5 stars, with critic Andy Kellman writing that on this box set, "despite playing roughly the same songs each set while knowing that they were being recorded, the band continually switched up the sequencing of the set lists... and the musicians played loose enough to allow for some spontaneity and variable interaction" and "the whole gang is at the top of their game".

[2] In The Boston Globe, Colin Fleming praised several elements of the performance and ended by stating that "vintage audiophiles will just about bow down before the quality of these tapes".

[3] Douglas Wolk of Pitchfork Media rated this album a 7.9 out of 10 and stated that "a 35-minute, six-song Live at the Fillmore East would have been a drop-dead classic on the order of Sly and the Family Stone's next three actual albums, or nearly so... but if you care about Sly Stone in 2015, after decades of dashed expectations and bungled comebacks, you probably care enough to want to hear the outtakes and alternate versions from the album-that-might-have-been alongside the real thing".

[4] In PopMatters, Joe Sweeney wrote that the band "sounded like a perpetual motion machine far too powerful to ever break down" and rated Live at the Fillmore East October 4th & 5th, 1968 a 9 out of 10.

[5] Relix's Jesse Lauter worte that "the energy on these tapes is undeniable, displaying one of the most formidable bands ever assembled".