I personally don't care about reviews but always check them out to see what the general consensus is.
It's always good to see our favorite games get high scores because it means the mainstream audience is more likely to adopt the game thus increasing sales significantly and allowing the development of future games in the franchise.
That, and it gives the game publicity. I think the MK team did well in that department though, considering their budget.
The reviews I am myself going to check are IGN, GameSpot, Eurogamer, Giant Bomb and 1Up.
Giant bomb will surely do a broadcast of anywhere from 30 to 1h30 of the game as a review on top of their written review, and are generally less biased than other sites lately.
I read 1Up just for giggles and never really trust their reviews.
As for IGN and Gamestop, they'll give a pretty similar score, like they always do, and nitpick on small details.
Finally, Eurogamer tend to be REALLY severe when it comes to games, which I really like since there's not many websites brave enough to be as direct. I think they'll give it a fair score, though.
~Khanada