The National Championship year was my senior year, so I have some decent perspective on how the offense was perceived at the time.
Obviously, we all thought that we had the best defense in the country (and we did, by far). We also had some great special teams that year, and not just Woodson.
As to the offense, I would say that they were a 6 of 10, putting them at just above average for a BCL-level (yes, pre-BCS, but you know what I mean) team. That offense was still better than 75% of the teams playing in D1 in 1997. They were just not flashy. More often than not, they picked up big 3rd downs, and they didn't really stall out for more than 1 quarter of any game. At the time, I never really remember being frustrated by them, and I was fairly confident in their abilities to score when needed.
So, above average to good, but not great.