BF3 and MW3 brought absolutely nothing new from its previous titles, and they get 9's for being cliche bro shooters. IGN dumps on Sonic simply because the reviewers' game preferances. There really isn't much to critique here, Sonic Generations was a great game.
*sigh. It's too bad Sega seems to believe IGN in that all the other Sonic playstyles were bad. I loved playing as Knuckles, personally.