There are many other apps out there that are good for fretboard work. This isn't one of them. Do some research, and keep looking.

Sound is terrible. Needs descending notes.. Needs more positions on fretboard and needs extended scales. Jam option has no music behind it so it's of no value at all.

Bad sound , doesn't play the scale descending , only shows one position, the jam part is a joke it's just you playing with the bad sound there are no other instruments to play along with