A special rig, designed by Robino films, enabled both a £2,500 Canon EOS 5D and iPhone 4S to record exactly the same shot for a comparison.  The results are surprising.

It's fair to say that the video alone provides much more camera based incentive than any amount of lucratively worded Apple marketing literature.  The two (on Vimeo at least) look near indistinguishable.  Of course, if you take a magnifying glass to it, the 5D wins.  It has greater depth of field, detail and it doesn't suffer from the iPhone's shutter problems, then of course there's all the manual settings on the 5D that the 4S lacks.  However, the point is clear: Apple has created a camera that can shoot pro-grade video (if a limited on options) that can compete with over two grand's worth of kit, for half the price and in a phone.  See the video below:

iPhone 4S / Canon 5d MKII Side by Side Comparison from Robino Films on Vimeo.