The DRM kills the feature for me.
You can only use it once, within a year of the movie coming out, and if your system dies or you delete the file, you're SOL.
At that point, you might as well download an HD version of the film and call it a day.
I was all set to argue with you, but then I decided I probably misunderstood what you meant. After re-reading it, I assume you mean you can only download it once, and it has to be done within a year of purchase.
I recently bought The Incredible Hulk on blu-ray and it had a digital copy. I just spent several minutes going through the fine print and it doesn't say anything about dl'ing only once, but it does say the code for Itunes may be invalid after 10/31/09.