I have been using this for over a year now and find it to be spot on. Having just changed phones I emailed CamerAlert in the evening to change my details and the following morning it had been done. An excellent product with excellent back up.
CBRonda, iPhone
Works well on the HTC Wildfire. I like it because it works, just using voice instructions with the screen off or with other apps in the foreground. It has a host of options to adjust for individual requirements.