Iron Maiden’s Adrian Smith says he was “kind of dreading” the prospect of being part of Iron Maiden: Burning Ambition , the new documentary about the band that’s opening May 7 in theaters worldwide. But the guitarist is pleased to report that he “was pleasantly surprised” with the results. “I enjoyed it,” Smith tells Billboard via Zoom from Turks and Caicos. “It’s a pretty deep dive. It’s great for the fans to have this.” And, he adds, it’s nice for the members of the band as well. “For me, personally, it’s nice to see the old footage,” Smith acknowledges. “It’s like another life back 40 years ago, whenever. There’s some things in there that are discussed more thoroughly than it’s ever been. It’s an interesting piece, I think.” The film comes on the heels of news that Maiden will be inducted into the Rock & Roll Hall of Fame on Nov. 14.…