I actually like the quality of the downloads on my iPhone and the fact that they don't take up nearly as much space as films I've bought from iTunes.
What does bug me though is that I've downloaded the film to my phone so it should work fine offline but my downloaded films will only work when I have wi-fi. I have the same issue with downloaded programmes on the BBC iPlayer app. Is this likely to be a problem with how the apps function on a 4S or is it perhaps the result of a setting on my phone that I could change to watch these offline?
Try updating the Flixster app, that was an issue, but they fixed it so you can access downloaded films offline (but only from the last account used to log in)