The score isn't the issue. Look at the GameSpot review. His biggest complaint is that enemies have idle animations so it takes actual timing to shoot them. This is supposedly a problem for some reason. He also complains that the characters don't "level up or change" while admitting that you can get them new gear and weapons, but apparently that doesn't count because they aren't absolutely necessary for progression.
Of course this happened. GameSpot set a complete nobody to review the game. As far as I can tell, this is only his second review for the site -- previously he was a writer for Paste Magazine. Compare that to IGN, who gave the review to Jose Otero, the head of their Nintendo coverage and a longtime writer for IGN and, before that, 1UP.