I still can't get over how awesome and useful this feature is. To be able to take a picture without touching the camera, or having anything dangling from the camera. This feature comes in especially handy for those long shutter speeds and bulb mode.
I love how on this camera I can change pretty much all the buttons to do what I want them to do. I agree with a number of people who claim the Sony menu system is a little awkward and for that reason the custom buttons are so useful. If I'm not mistaken I don't think any of the buttons do their factory function any more, aside from the shutter button of course.
Built in Remote control
Having the ability to control your camera using a smart phone/tablet opens up so many creative possibilities. I can't think of many (if any) shoots where this feature has not come in handy. Also the ability to review images on a tablet means you're not all huddled around a small screen to see if the images are any good.
I think this feature has been severely underplayed, the fact that these cameras have dedicated app stores is just phenomenal. The store is still in it's early stages and probably not where it needs to be, however it's a huge step in the right direction. We may be looking at the dawn of smart cameras. Currently there aren't many apps available, however the few that are there, I find to be very useful.