This is obviously a coup for Seattle. The two time defending NFC Champions now add the best tight end in the conference to their team. This deal, and resigning Marshawn Lynch, make the Seahawks the prohibitive favorites to get back to the Super Bowl for the third season in a row.
As for the Saints, I believe this is the end of their window. They face salary cap concerns already, and trading Graham will help that some. But you cannot replace a player of that caliber easily. The vaunted offense from two years ago is gone. Drew Brees is not what he was in prior seasons. Darren Sproles is gone. Marques Colston is a shell of himself. Not Jimmy Graham is gone? Add to that a defense that is barely competitive? The Saints may be the third best team in the NFC South now. (Nobody deserves to be below Tampa Bay.)