Actually BzN in a P40 isnt all that great. You can dive from altitude many thousands of feet and start a climb back up, and have the LA7 you dove on climb up to you.
In my opinion it works best to fly it defensibly and sucker in the victims. But like others have said, like many planes in here you cant hop in one and expect 5 kills every mission. You need to fly it alot. Everything from learning what you can outrun, (not many) and what you can't(most) to learning how to aim, using flaps,avoiding hits.
Some people would never like it though as it doesnt have cannon and it isnt a speed queen. Its really for the people who fly for the fight.