Well, I don't believe John Paul II was the Antichrist - too many things don't add up. Obviously, I don't expect the Antichrist to match 100% the predictions about him in Catholic Tradition, since that would make him too obvious to deceive people. Nevertheless, I expect some sort of compatibility between traditional eschatological predictions about the Antichrist and the actual Antichrist.
Antichrist's reign should be short, JP II's pontificate (or, quite possibly, anti-pontificate) was longer than all except that of Bl. Pope Pius IX. At the end of his reign the Antichrist will be defeated (if I recall correctly Our Lord promised one of the religious orders a crucial role in defeating the Antichrist, can't remember which one though), while John Paul II died of old age for natural reasons. Finally, we are 11 years past the death of John Paul II and...? Many other problems could be pointed out.
Too many serious discrepancies for me, but I am open-minded and willing to listen to arguments.