HP had a good write-up about what USC has done so far this season on offense ("the best offense ever").
Here's another good piece from USA Today, looking back at the defensive coordinators who have faced USC this year and their reactions. Quite interesting, and paints a devastating picture about just how much USC can do on offense. That's one of the things I like to look for on an offense---balance running, passing, using the entire field, ability to run and pass at will, in any formation, changing tendency, but also having some bread-and-butter stuff to fall back on.
And if that's not enough, USC is just so well conditioned and has such a veteran quarterback that last line of defense of theirs tends to make the difference if opponents can get beyond all the scheme and big names.
The Trojans aren't perfect, but they do so many things well its really hard to box them in over 60 minutes. It's been fun to watch so far.