Ass kicker, when flown properly.
The Finns had several things going for them... Russian tactics, at least through mid-1943, were very rigid and inflexible, largely prohibiting freedom of individual action so the Finns could dance in and out of Russian formations, picking off aircraft at will. The Russians also had formation command problems; most Russian-designed aircraft were fitted only with a radio receiver. The Finns were also very highly motivated... the Soviet Union had bullied them into conflict, expecting the Finns to roll over like Estonia, Latvia, and Lithuania, but Stalin seriously underestimated the Finnish sense of national identity and their fierce determination to protect it. Consequently, they absolutely decimated the Russian forces. And I wouldn't call Spitfires, Hurricanes, Airacobras, LaGGs, and Yaks "inferior equipment"!
On the Allies' side, we made a number of mistakes with the F2A; we weighed it down with armor and other equipment without a corresponding increase in engine power, and we had no idea how to properly fight the ridiculously nimble A6Ms and Ki 43s until late 1942. By that point, all of the British squadrons had been overrun, and the Marine F2A-3s had been decimated by the IJN due to poor fighting tactics on our part.
I think the real bottom line is, don't f**k with the Finns!