Well the Giants defense shut him down twice. most people think this Seahawks defense is better even than those two giants defences. they will probably win.
I would not say that the Seahawks are favorites. The Packers dominated them for 3/4 of the game but managed to fuck up basically everything in the last 5 minutes. That was no great comeback by Seattle but an epic failure by Green Bay. And they had Rodgers playing on one leg after his thigh injury.
Brady and his offense are surely capable of scoring plenty against any defense. The odds are pretty even.