Niners have a ton of momentum and experience playing in Seattle, but they have, in recent history, struggled there. The players, for the most part, hate each other..and so do the coaches. Both fan bases have made moves to disrespect the other team during the season and are sure to be incredibly rabid up to, during and after the game, regardless of outcome.
It will be intriguing to see if Percy Harvin suits up and how he is used if so, as well as any new wrinkles and tricks both coach may employ that the other team hasn't yet seen. Should be a hard hitting, smash mouth game.