I think Johnson will prove to have been one of the top 3 free agent acquisitions league-wide when the 2006 season is in the books. What Steve Smith should be able to do with someone of his caliber across the field, taking into account what he was already able to accomplish last year with guys like Colbert, Proehl, and Drew Carter, should be off the charts.
The "distraction" angle that the Falcons fans are taking seems like equal parts desperation and lazy research. Johnson's reputation as a "distraction" is terribly overrated and seems to stem from his controversial quotes regarding Chrebet almost a decade ago, and his disagreements with Gruden in Tampa 3 seasons ago. Everything else regarding Johnson involves hard work, passion, and willingness to be a team player, from what we saw up close here for 2 seasons.
The only caveat--tell Delhomme to put in some earplugs, because he'll have two well-meaning but loud and emotional guys asking him for the ball all the time!