Seems to me he got his money's worth:
The combined overall household rating for Senator Barack Obama’s Wednesday night infomercial, in the top 56 local television markets where Nielsen maintains electronic TV meters, was 21.7. [...]
In comparison, the final debate between the two presidential candidates received a 38.3 household rating in the top 56 local TV markets. The candidates’ first debate on September 26 received a 34.7 household rating in the top 55 markets; their second debate, on October 7, received a 42.0 household rating in those markets. [...]
One rating point equals 1% of the total TV audience in a given market.