A lot of the material out there on German "wonder weapons" is overhyped or simply invented. There were significant advances made in aircraft, though, and the Horten Ho229 would have been a big leap if it had gone past the prototype stage and into mass production. Enthusiasts at Northrop Grumman built a replica from German blueprints and the materials available in 1945 Germany. They found that, as advertised, the plane would have been hard to pick up on WW2 radar.
COMMENT: Would it have won the war? No. The Allies would have beaten it the same way they beat other German jet and rocket planes - using the numbers and range of their fighters, especially the P-51, to shut down its airfields and ambush it on takeoff and landing. But it was one heck of an impressive technological advance, and it would have driven the Allies to distraction for a while.