In return for Reggie Bush, Saints received former Dolphins safety Jonathon Amaya and a swap of undisclosed draft picks.
Without knowing what the draft picks are, this doesn't tell us a whole lot. Amaya definitely had his moments on special teams last year, but he was an undrafted free agent in 2010 and didn't even make it off the practice squad until the end of October. He's a fun player, but hardly a core piece - not that one should have been expected in return for Bush.
As for Bush, the question is what his role will be in Miami. Matt Bowen notes that Bush won't play every down in Miami, and will instead be used sparingly, with the hope of racking up big plays as a change of pace. He'll also continue to be involved with returns.