With over 1 million apps in the Apps store, it's hard to make your app stand out. Our testers tell us that they sometimes use downtime to browse the app store but most often they are scanning quickly for an app to fulfill a particular need. They are in 'fast flick' mode. So what catches their attention? Names they know and icons which give strong scent about what the app can do for them.
If a user wants to be confident an app will do what it says it will they'll look for a familiar name and a reputable brand. So if you have one of those make sure your app icon reflects that brand. If you are smaller fry your brand needs to appear appropriate to the category of app.
Our testers showed us that there are lots of app icons which don't clearly say what they do. It's no use standing out from the crowd just for being whacky. Some icons use clever or obscure imagery and branding. Our testers flicked straight passed those. Getting noticed is important but it has to be for the right reasons. This is not the time for designers to get cryptic, the icon must clearly communicate what the app is and what it does.
That doesn't mean you 'can't apply some great design. The icon needs to be enticing and memorable. The design should reflect the nature and 'personality' of the app. But it still needs to be meaningful. There is no point in having a good-looking icon if it doesn't say what you do. Users go for eye catching and understandable ('that's the app for me') and not for eye catching and cryptic ('what's that all about?').
Our testers needed an app icon to convey the true essence of the app all in one image - what do I really need to know about this app? And it's good to test this with 'real' users to make sure you've got it right - app icons which indicate a view of the world from inside the organization and not from a user's perspective stand out a mile, but for the wrong reasons.
In summary, an app icon with strong branding, simple but good-looking design and that says what it does, will be the most eye-catching and memorable.