While I'm not sure I would like to make the final choice in terms of greatest combat flying feat ever, I will say that the gliders at Pegasus Bridge episode actually came well recommended.
The 'greatest flying feat of the entire second world war' quote is actually from Air Chief Marshal Sir Trafford Leigh-Mallory who was commanding the Allied Air Forces on D-Day. Praise indeed for a 24 year-old Army NCO pilot from a Royal Air Force 4 -star!
As an aside, the pilot of the lead glider made the trip at night, on stop watch and compass only, at a weight he had never flown his aircraft before, using a parachute arrestor system he had never used before and point landed the aircraft to within single feet in order to exactly cross a barbed wire entanglement and allow troops to cross it and assault the bridge. When the aircraft came to its final halt, he and his co were thrown forward out of the cockpit into the ground and in doing so became the first allied serviceman to touch on French soil as part of the invasion force.
Good work by SSgt Jim Wallwork DFM Glider Pilot Regiment who I believe is still alive and lives somewhere near Vancouver.
One of many heroes of that generation.