I personally didn't care for Bioshock, and I think the sequel will be rated much lower than the original, as many of the original's unique concepts won't be so unique now (the illusion of choice, the genral setting, etc.). For similar reasons the unique and innovative Patapon scored considerably higher than its sequel. I see Bioshock 2 barely breaking a 90 average.
As for whether it's the highest rated game of 2010, I think the following will score higher:
Super Mario Galaxy 2
Zelda Wii
Halo: Reach
Gran Turismo 5
God of War III
And maybe Metroid and the Last Guardian. The former could go either way with Team Ninja's involvement, and the latter titles generally receive somewhat mixed scores.