The main negative finding in Kevin R's careful review was that your iPhone may fall off the Camera unit if you hold it but not the iPhone. DXO's reply to this (in a video linked to the review) seems to be that if you are going to operate one-handed, you should hold the iPhone, in which case the Camera unit is too light to fall off. On the face of it, this seems at least worth considering as a response. I wonder if there is anyone who has tried it.
