Sonic for 360 sold 102,250 copies in December. This is well more than 2x November sales. However, I think this game may have been bought more as a gift and so this is not indicative of actual gamer demand. Sonic is now at 141,750 copies sold for North America.
My comrade just got finished playing this game. He told me that the graphics were amazing, but that the controlling the characters was difficult.This game definitely has nostalgic appeal, but from what I've heard about this game, it doesn't look like a solid title.
3
http://www.vgcharts.org/usagamemh.php?name=Sonic+The+Hedgehog