I'm hoping when the fall comes they offer the current episode free, such as if you miss a recording. I saw a user at dbstalk compare the price of watching a season in HD on D* costing $24-$48, compared to buying a DVD set for $50-70 for a season.
The problem is - the DVD set you get to keep, the VOD is a 24 hour view only.
I think it has great potential for the fall if you like a series and miss an episode. For example, I like The Office and DVR it every week. If I ever had a conflict, failed recording, or bad weather/lost signal, I'd pay 99c or $1.99 to watch it for that time. I wouldn't do it often, but on occasion, maybe.
If they launch the other networks in this same manner, I'd probably feel the same about those too. I wouldn't use it much, but it is still nice to have the capability when needed