This is just a tremendous article by Chris Brown of Grantland / Smart Football. A quick excerpt:
"It will be a weapon for us and a tool in our toolbox," Kelly said of the fast-paced no-huddle after the game, according to the team's website. Even at Oregon, Kelly's offense had not one but three speeds: red light (slow), yellow light (medium: team gets to the line but quarterback can slow it down and change plays), and green light (superfast: get to the line and run the play). Good defenses will adapt to any pace, but a good no-huddle - whether it's Kelly's Eagles, Peyton Manning's Broncos, or Tom Brady's Patriots - will vary the speed, using it strategically, waiting to put its foot on the gas pedal precisely when the defense has the wrong personnel stuck on the field.
Against the Patriots, the Eagles didn't use a lot of their superfast tempo, but when they did it was effective. About midway through Vick's first drive, the Eagles sped up the pace after a 22-yard completion to Jason Avant, and two plays later Vick hit DeSean Jackson streaking down the right sideline for a touchdown. After the game, Vick talked about how the Patriots had been trying to disguise their coverages, but the quick tempo helped force the Patriots safeties to show that Jackson would be single-covered.
I won't ruin the rest of it. Just go.