I think this could be incredibly useful. There are ~315,000 species of plants identified by botanists; if you have the spiritual insight to identify them all good for you. The rest of us might appreciate a more practical solution. No one will need this for plant they already know and have an understanding of. It is the ones that we haven't seen before or haven't been able to find in guides.
I don't see how this is practically any different from a field guide.