I managed to produce drawings on paper which were vast improvements of what I would have been able to draw on paper in the past. There is a learning curve to use this app and some jury rigging involved. For this app to do its job you need a stand to keep the iphone steady. This will likely make it impractical to use with an ipad. Ideally it should be mounted on an offset arm to allow for total coverage, if not, the stand will be in the way of the drawing hand. There is an appreciable lag between the hand drawing on paper and its image appearing on the screen which complicates the hand to eye coordination. Also, the final drawing size was small as it depends on the separation between the paper and the device... which brings things back to the stand.
Rebfel about Camera Lucida™: AR Drawing, v5.1