The CBS affiliate in Minneapolis, MN, WCCo-TV, compared Blockbuster Online and Netflix for three months. It's the usual yada-yada except for this bit:
"When it came to delivery, Netflix beat Blockbuster. In a three month time period, Blockbuster only beat Netflix once, and that was during the trial period.
As for the cost, it was $60 to rent 24 movies. To get the same number of movies from a video store would have been $93."
Hacking Netflix beat me to it.