I think the Pats will win, based on everything I've read, but there are a few things that do worry me.
(1) Belichick seems to do best against teams he's familiar with, which does not include the Falcons.
(2) The Pats have a way of keeping Super Bowl games close, even if they are superior.
(3) The Falcons are supposedly a hard-hitting team, so injuries could be a problem.
That said, from what I've read is the Falcons have small corners and their pass rush is overstated (mostly effective against QBs who hold the ball awhile). While they may have a slight edge on offense, we have a big edge on defense. I think the Pats should win pretty easily, but there are certainly enough variables for there to be an upset.