I've always been a great fan of the Iphone for day to day personal photography. The apps that are available make image manipulation very straight forward and the creative options are pretty much limitless and improving week by week. Images out of the new Iphone 5s are a very respectable 3264x2448px and given the right shooting conditions and light, images can really be very good.
Straight up images from the standard camera app are ok, but nothing special. Shoot via an app such a VSCO and suddenly you have independent control of exposure and focus point - something currently not available with the standard camera. Images take/processed with apps such as Hipstamatic or Snapseed suddenly take on whole new dimension and have the ability to sometimes make the ordinary image extraordinary. OK, so maybe a client might not look favorably on you turning up on a shoot with just your Iphone in hand, but as a backup or second camera in certain situations it can produce some very printable images. As a discrete tool for documentary work the iphone is fantastic - everyone these days has a smartphone and no one thinks twice about people shooting images with your phone. Produce a 5d mklll with a large zoom lens and people immediately know you are meaning business and these days, even in remote areas, that can be met with suspicion. I now often break the ice with the Iphone camera - showing people the images and developing a rapport. Once this is established the main camera can be brought out and used.
My current favorite workflow is to use Snapseed for image manipulation and output - having first shot in either VSCO or standard camera mode.