He has 200 million a.k.a. the most football crazy nation in the world and a lot of politics behind his back who want him to be "better than Messi" and "the next Pelé". The fact that it's by chance the footballing rival nation of Messi's nation makes it even worse. He will never accept the fact that this team is built around Messi. He will try to play for his own glory. At some point he will. It's inevitable. Even if he wasn't a cocky and arrogant bastard himself, the politics behind him will influence him. Pelé will give interviews every week how Neymar was the better performer on the pitch and not Messi and so on. It will divide the fans as well and cause a lot of turmoil. Imagine Messi and Neymar fighting for 1. and 2. spot for the Ballon d'or. This won't end as well as Xavi and Iniesta competing for it, being homegrown and genuinly humble guys who care for the club and not their own glory. If there is a CL final on stake and there is the option to pass the ball to someone better placed or go for his own glory: this is the type of player which will prefer the latter.
Would I be excited if he signed for us? Damn, I would. But it's a classic case of: "Heart says yes, brain says no." I'd rather prefer him to stay at Santos until 2014, flop with the Brazilian national team in his own country and then go on to Real Madrid to officially fulfil his destiny as the next stepover artist who succeeds Cristiano Ronaldo when Cristiano hits his 30s and starts to decline.