Your App Icon needs to stand out on today’s crowded mobile devices. More importantly how do your icons extend your brand? Does it work with your overall brand strategy?
The App Icon is a unique expression of the app - and your brand. In fact, much like Facebook, putting their mark in the App rounded-square, your application icon could be the most important iteration of your brand. How do you make it consistent with your brand values AND stand out on the home screen (or springboard)?
How your App Icon looks - big or small, light or dark, subtle or contrasty, thick or thin lines, monotone or colorful, flat or skew-morphic, or some combination there of is more important than you might know.
This great article on App Icon design will at least help make sure your icon gets noticed. The brand values are up to you:
Designing better app icons, by Michael Flarup