1) While the app does work, if you are attempting to take a picture with one hand, it still requires hand gymnastics (which is difficult when you are cycling and attempting to take a photo)

2) the Vol+ button isn't a 2-step button like most hardware camera buttons; it's difficult for a software solution to compete with hardware solutions in cases such as these. I'm still trying to get over the loss of the HWKB going from the N900 to the N9.