Not for everyone.
It might be useful for studio photographers. If you mount the 'lens' on a tripod, you're free to walk around with an ipad as remote viewfinder. You can be in front of the camera while you adjust/reposition your subject, mess with lighting, etc., as you hit the shutter. Who needs an assistant anymore?
Or you can unobtrusively hold the lens above your head at sporting events with your ipad on your lap. That should please some folks.
This already exists for DSLRs, which would be far more useful in a studio for a pro, with their nice $2500 lens.