I saw him fight a few months ago. The announcer said his PSI punch power is the highest of all time. Not only does he have a huge height and reach advantage, he also packs a massive punch. I agree with Oscar in that the key would be to stay in close and not allow him to get full extension with his punches. Even then, the if the guys stands fairly upright the whole time, it will be pretty difficult to land a full power/extension punch to his head. I have been active in martial arts for about 10 years now and I confidently can say as a experienced fighter that I would have no problem turning tail and running like hell from a guy like this. He is just too big and powerful to mess with trying any close combat with. I also think that any attempt to take out his legs to even the fight would be extremely hard due to the fact that he is just so heavy.
In short, I think he has the potential to be one of the more dominant heavy weights in history. Just ask Don King, it seems he is already on his bandwagon.