I find it interesting to discover there are guys nominating the He 177 and the Bf 110 to get the overrated tag.
First off. The He 177 never saw action in any significant numbers. Like most planes going through developtment, it had its shortcomings, most of them got corrected. Also there is absolutely no evidence that could help you affirming the Germans ever said it was a wonderful bomber.
So the overrated tag does not fit in the case of this particular bomber.
The Bf110 was certainly a plane with high expectations placed upon it.
Fared very well during Fall Weiss, Fall Gelb and the battle in Norway, to take a mauling during the Battle of Britain.
Overrated? Not at all. It was like if you were affirming the pilots, officers and commanders of the Zerstorerwaffe were idiots. They immediately learned it could not manouver the way of both Hurricanes and Spitfires.
The Germans would eventually find the hunting ground more than suitable for the Bf 110: the night fighter role. I can assure you many RAF bomber command veterans will argue the comment the Bf 110 is overrated.
It had a fearsome punch in the nose, it was fast and had a large range.
The Spitfire is certainly an overrated plane. Its glorious episode was a brief one, known as the Battle of Britain. From 1941 to early 1943, the Channel/France region became a secondary theather of operations for the Luftwaffe. 1941 was the year when the strenght of the jagdwaffe was deployed in the east.
1941 sounds likely to have been the year for RAF fighter squadrons to rest, refit and to have their suffered wounds licked after the BoB, for after all, they took a mauling there as well, and the enemy was by then working heavily in the east digesting the soviet air force.
But if you conduct a follow up research on the performance of RAF fighter squadrons from 1941 to late 1942/early 1943, when they faced the "Schlageter" boys of JG 26 and those of JG 2, they proved uncapable of repeating the deed of 1940, suffering tremendous losses at the hands of both the Bf 109s and the new Butcher bird. (i.e. The Dieppe raid and the Channel Dash of the Scharnhorst and Gneisenau can help as evidence)
I am convinced the bottom of the channel contains far more carcasses of Spitfires than of any other plane who saw action in the area.
It was not until the build up of the USAAF had begun in the island when Spitfires showed any improvement.
However you can never compare the Spitfire case with that of the IL-2.
The propaganda of the soviet union took the Il-2 up to levels if insanity.