Well we went to the race and as skeptical as I was I had a blast. I still don't care about racing, but it was fun to care about that one. I like that it was a somewhat important race. That it meant something.
Some tips for those like me who don't follow racing... The first 15 laps or so are the most fun! So don't miss them. At the start the cars are still fighting each other. After that the leaders seemed to have already won. So the next 40 or so laps can be a bit boring. For those laps experience the atmosphere. The atmosphere at the race before the race is electric.

It is fun. And for the 40 somewhat boring last laps there is still lots of fun stuff going on.
Regarding Austin over the weekend, it seemed slower than normal weekends. Like there was lots to do, but not as many people as our average weekends. It was weird. I blame the state and the COTA people. If they wanted as more Ft Worth type Texan atmosphere they should have built COTA in Arlington. There was way too much trying to pass Austin off as Cowtown full of cowboys and cowgirls.
Austin isn't Ft Worth. If the organizers are going to try to make Austin into Ft Worth for a weekend then Austinites are going to stay home. It just didn't seem to work for Austin businesses because it isn't our style.
Regardless of the efforts of the organizers to make Austin into Ft Worth everyone I know that came to town LOVED it! They loved everything about their trip.

They loved the people, the race, the city and the track. All the rest of the stuff like trying to promote Austin as Ft Worth can be easily fixed. The important things about having good people, city and track that all of which blew the visitors away are in places. I think COTA has a great future.
Edit: another tip...
Take ear plugs! It is super loud!