I see Pixar are doing a 'rat' film: their's have beautifully animated fur, while these don't even have combed plasticine 'fur'.
I saw the trailer for both afterwards and there's an interesting difference between 'FA - the trailer' and 'FA - the film'.
In the trailer, Rodney has two servants (e.g. he tells them to "go and warm the Jacuzzi.."). In the film, he doesn't have any non-human live companions.
Presumably they got cut out in order to make his plight - being alone, without a 'family' - more credible. "Who do you live with?" "Oh, erm, well, my family... and two servants!" Not quite as good.
But it's interesting that their sequences were fully animated before this happened... or was this done specially for the trailer to increase the effect of the 'luxury to sewer' transition?