It seems like a great value option to me - I'll be getting one next time round :-)
The problem with it is, it takes a bit of time to open and start, sounds really noisy as the cover opens and the camera emerges and can go wrong as shown by a few posts. I still think it is a gimmick, though quite cheap to factory order. So, why not.
But still worth having reversing sensors in case the camera malfunctions.
Not sure how many you have experienced but my experience is completely different. So without being accused of jumping on you,

I totally disagree. Opens the second it goes into reverse, the noise is the same as someone lifting the handle to open the boot (better than the sound of hearing the bumper grate along a wall) and I've never had any problems with mine. My only gripe would be it tends to mist up in certain weather conditions but still very usable.
I can reverse to literally within a couple of centimetres of the car behind me safely knowing I won't hit it.
Would I buy another car with that option? It would be the first option I would look at.