Marissa Mayer has this to say on the simple yet intuitive user interface of Google (and these words apply to the iPod as well).

Google has the functionality of a really complicated Swiss Army knife, but the home page is our way of approaching it closed. It’s simple, it’s elegant, you can slip it in your pocket, but it’s got the great doodad when you need it. A lot of our competitors are like a Swiss Army knife open–and that can be intimidating and occasionally harmful.