Instagram and Hipstamatic are two great apps for giving a retro look, but I think that when used too much you end up with a bunch of images that can all look quite similar.
I think it is important to use all of the tools in your tool box, rather than depending on just a couple for your photography. Photographing finished dishes with these apps can work OK, but I prefer finished dishes to look clean and clear.
That said, I think there is a couple of situations where these apps shine, and my favorite use for them is photographing produce and people.
Both apps give you some control over some lovely post processing effects, and these effects can really help to add atmosphere and feeling that is very evocative of the emotions of a situation.