At Fillmore East jazz. "Fusion is a term that came later, but if you wanted to look at a fusion album, it would be "Fillmore East". Here was a rock 'n' roll band playing blues in the jazz vernacular. And they tore the place up," said Dowd. Announcer Michael Ahern opens "At Fillmore East" with a simple introduction: "Okay, the Allman Brothers Band." Duane Allman biographer Randy Poe describes it as "the only low-key moment over the course of the [show]." The cover of Blind Willie McTell's "Statesboro Blues" which opens the set showcases Duane Allman's slide guitar work in open E tuning.
At Fillmore East Stephen Thomas Erlewine gave the album five out of five stars and stated, "[it] remains the pinnacle of the Allmans and Southern rock at its most elastic, bluesy, and jazzy". Mark Kemp of "Rolling Stone" gave it five stars in a 2002 review and commented that "these shows [...] remain the finest live rock performance ever committed to vinyl", and the album "captures America's best blues-rock band at its peak". "At Fillmore East" was one of 50 recordings chosen in 2004 by the Library of Congress to be added to the National Recording Registry. "Rolling Stone" included at number 49