Blaine, 35, ended his latest stunt by appearing to vanish from the structure where he had spent nearly three days -- most of it hanging head down.
Having completed the promised 60-hour period, he leapt from the metal frame holding his cable, then was hoisted back into the dark sky, giving the impression of disappearing.
Some in the crowd attending the finish grumbled that Blaine exaggerated his feat, because he wasn't actually inverted the whole time.
During much of the period he stopped for regular breaks on his feet -- as often as once an hour -- to drink liquids, urinate and undergo medical checks.
"I am totally unimpressed," Joshua Yoselowitz, a 31-year-old banker, told AFP. "I'd rather be at home. If his name hadn't been David Blaine I would never have come."
Undoubtedly the hanging stunt was a physical and mental test.
The daredevil magician has previously spent 72 hours encased in ice, 44 days in a plexiglass box, a week under water, and been buried alive. But he told AFP at the start of the challenge Monday that he'd faced nothing harder.
Blaine apparently did not sleep for two nights and he spent nearly the whole period suspended the wrong way from a wire attached to a body harness and special boot clips.
His doctors had described a very real danger of blindness and swelling of the brain.
Several hundred fans cheered at the climax, which was broadcast live on ABC television.
But Blaine did not stick to what many assumed would be the strict format.
Instead of permanently hanging upside down, Blaine took numerous rest breaks on a platform brought to him by a hydraulic boom.
During one such moment, a few hours before the finale, he spent 20 minutes on his feet.
First he could be seen drinking an orange liquid, then he urinated behind a sheet held up by an assistant, and then he underwent an eye and heart check by a medical attendant.
An hour later he took another, briefer time-out.
The pauses brought howls of derision from some in the crowd.
"Oh, so this is where the magic comes in," said one heckler.
"Come on, do a trick!" shouted another.
New York tabloid the Daily News passed its own verdict, saying: "Some folks are already saying the achievement should be marked with an asterisk."
ABC, the US network that owned the live TV rights, brushed aside the issue in its two-hour live coverage of the ending to the stunt, dubbed the "Dive of Death."
When Blaine was brought to stand on the platform for his final dive, the ABC presenter inaccurately announced: "You can see David turned upright for the first time in 60 hours."
Yet fans inspired by Blaine's eye-popping card tricks and powers of illusion said complaints were mean-spirited.
"I think he's awesome. He's giving to his fans, he's showing he can do whatever he believes he can and we're here to support him," said David Mercado, a 39-year-old construction worker. "Give the guy a chance!"
Maria Romedo, 58, agreed. "You can do it David!" she shouted.
Blaine says his hero is Harry Houdini, the legendary escapologist of the late 19th and early 20th century, who amazed New York crowds by hanging upside down from skyscrapers and cranes in a straightjacket.
Other than the publicity-grabbing stunts, Blaine is known for pulling off illusions, including transforming a homeless man's cup of coffee into one overflowing with coins, and appearing to have magically removed a distraught-looking woman's front teeth.