For the occasion they performed all the songs in order from their first two albums, The Allman Brothers Band and Idlewild South.

The show features the 2001 to 2014 lineup of the group – Gregg Allman (keyboards, vocals), Warren Haynes (guitar, vocals), Derek Trucks (guitar), Oteil Burbridge (bass), Butch Trucks (drums), Jaimoe (drums), and Marc Quiñones (congas, percussion, vocals).

In Glide Magazine Doug Collette wrote, "... 40 is so impeccably recorded in audio and video (the latter of which makes an often cheesy light show look impressive), it is comparable to 2003's Live at the Beacon Theatre DVD... 40's skillful camera angles, including as many panoramic shots as face to face close-ups of the players, present a scintillating vision of a band that over the decades has lost, recovered and maintained its unity in such a way it's turned the passage of time into a means of transcendence.

"[1] Larson Sutton of Jambands.com stated: "Ostensibly the show is in recognition of four decades, but the real recipient of the tribute is Duane Allman and those two magical years he spent leading the group to glorious heights of blues-based improvisation... throughout 40 it's overwhelmingly obvious how respected he remains, how persistent his influence and innovations are on his current interpreters Haynes and Trucks, and how the Allman Brothers Band has endured in those subsequent 38 years.

"[6] Writing for Classic Rock Revisited, Jeb Wright commented: "This is a celebration of much more than a band's fourth decade of existence.