Could you phrase the question a little less subjectively?

Winged Hussars were heavy lancers which are fearsome only based on their opposition. Against poorly armed peasant militia? Terrifying.

Against say, pikemen? Not so effective.

They were heavy cavalry. Reading about the disadvantages of Heavy Cavalry will cover the Polish Winged Hussars strengths and weaknesses in a broad way.

I can find no evidence for them tying severed heads to their lances. In any context except use in a parade doing so would make the lance aim shake due to it having several erratically (not erotically!) moving weights attached. Even tying them to your saddle would be unpleasant and smelly. Headhunters have existed in many places in many times, but so far as I've read the Polish haven't been noted as practicing this tradition.