We have reports about this aircraft from North Africa. She was natural fodder for the I/JG 27 with Messerschmitt Bf 109E and F and the Macchi MC 202 Folgore of the Regia Aeronautica. Even with an old aircraft like the Fiat G. 50 it was not hopeless to fight against an P-40B or E. It depends on the scene. Her strength and nosedive were her good points. The rest was rather mau. There are also Russian sources, where the pilots received machines from English stocks. They weren't enthusiastic there either, and comparison flights with the Jak 1 and the MiG 3 didn't go so well either. Of course, it was a very good replacement for the Polikarpov I-16. But that was not the benchmark in 1941. The sticking point was the Allison V 1710, which was worse than the Klimov WK 105 and ran significantly worse at altitudes of over 4000 meters (!).
The Russian climate in the far north like at Murmansk killed these engines. The Soviets called it a time bomb. One of the well-known aces of the first months of the war died in a P40E due to engine failure, and word got around. Boris Safonov.
https://en.wikipedia.org/wiki/Boris_Safonov