A plus.
He's become a larger-than-life personality, and he knows it. Like many dictatorial types, he is obsessed with his own power, hence why he won't allow the Palestinian legislature and PM any real power, and why he has a bewildering network of different militias and security services to "maintain order."
He has singlehandedly set back the Palestinian cause for generations, by refusing the offer Barak gave him before the present intifada began. He could have arranged for part of Jerusalem, and something like 95% of the West Bank. Now that the Israelis have drawn the conclusion that the Palestinian Authority is not interested in peace, they will get less - and that will be imposed by the Israelis against their will.
The intifada he started / allowed to happen / encouraged / defended (depending on one's point of view) has been an unmitigated disaster for the Palestinians. The suicide bombings have destroyed much of the sympathy that the outside world once had for their cause. The Palestinian economy is in ruins - and what little is left depends on access to Israeli jobs. Thousands of Palestinians (and Israelis) are dead. The Israelis, far from being exhausted or beaten, have developed a "bunker mentality" and are disinclined to negotiate, favouring a unilateral solution.
Arafat had the opportunity, like Mandela, to lay the terrorist's weapons aside and use his influence and prestige to build a democratic, unified Palestinian society that the world could have respected. His legacy would have been that of a peacemaker, a nationbuilder, and a statesman. Instead, he chose to let the dogs of war slip yet again, and used his influence to gather more power unto himself. He will likely die in a hospital (with the acquiescence of the Israelis) or in his compound (surrounded by Israeli troops) of natural causes, and not as a glorious shaheed like he always talked about. And he will be remembered as an obstacle to peace, as an unrepentant terrorist, and as a failed dictator.
My two cents, anyways....