I have the Freddie Hubbard - Here to Stay release from this series and I remember it sounding pretty good. Here's what London Jazz Collector has to say:
Michael Cuscuna opens up the Blue Note vaults: the two-fers
Notable amidst this sea of variable quality reissues and a handful of new releases, the Blue Note vaults at this time yielded up many previously undiscovered original recordings from the Blue Note years, including sessions by Andrew Hill, Booker Ervin, Sam Rivers and many other gems discovered by Michael Cuscuna.
Around 1975, United Artists released these for the first time, in light brown gatefold package double album “two-fer” series. The series adopted a variant of the UA blue label, using a white b encircled by “THE BLUE NOTE RE-ISSUE SERIES”, a misnomer, as all the tracks have
never previously been issued. The sound quality on some of these two-fers is bright fresh and exciting (Van Gelder recordings), whilst a minority are somewhat lacklustre. Booker Ervin’s Back From The Gig is a stellar recording, essential.