They have presumably carefully thought about the price, and then quadrupled it to make it uncompetitive when compared to a DVD of the same film, which would be higher quality, viewable in a relaxed environment on a screen that doesn't give you eye-strain and/or run out of batteries at a crucial moment, and usable for as long as you want - all for about the same price from any DVD shop (a little while after launch - I tend to pay £5 for my DVDs which usually equates to $5 in the US).
They have two problems here:
Firstly, who in there right mind wants to watch a 2 hour feature film on their mobile? It's ergonomically very awkward - you have to hold it steady somewhere with a strong signal for a long period avoiding direct sunlight etc etc - and it'll trash your batteries. I can understand watching a 2-10 minute clip if you're stuck and bored, but 2 hours?
Secondly, that price point is absolutely ridiculous for a short term, low quality rental. Blockbuster offer as many DVDs as you want through the post starting at $5.99/month, and I'm sure a single film costs less in a shop. You are in theory paying for the convenience of streaming the film to your phone without having to go anywhere, but I don't see why you'd do it.
The one hope for this initiative, where it really could take off, is with a phone that can output to a TV - so rather than go to Blockbuster, you just plug in your phone to the nearest TV and watch away. Once the market is full of WiFi UPNP handsets and TVs, and once they become standardised and genuinely child's play to set up unlike all existing WiFi initiatives ever, this could be great. I can really see people wanting this service, if the price point is competitive with a normal rental and with broadband video-on-demand services (stop mentioning Kazaa at the back). However, what chance of this happening in the next few years?