Quite possible that you had a broken unit although surprised you could use the button to take pictures but not launch the camera app.
A gentle press is meant for focusing when the camera app is open.
This opens the camera app if it's not already open.
Autofocus is screwed due to beta version of camera app, sorry for that....
On all five model generations, the phone can be configured to bring up the camera app by quickly pressing the home key twice.
Beginning on iOS 5, sliding in the other direction sends the user directly to the camera app.
A unique feature in the Z10's camera app is TimeShift.
Especially when starting up the camera app sometimes and in mail.
The front camera, which is accessible through the FaceTime and camera app has a lower resolution, at 1.2 megapixels.
The camera app includes a new shooting mode known as Zoe (alluding to the zoetrope), which films 4 seconds of video alongside every photo taken.