That something would be making the user experience "smooth". I had an assortment of PalmOS devices, played with WinMo devices and settled on a Sony Ericsson P-800 which was my main phone when the iPhone was launched. I could anything an iPhone could do, but I didn't have transitions, scroll inertia and drag to scroll. The P-800 was good, but the iPhone was great.

It's very easy to assemble a set of functionalities. It's not easy to make it fun to use.

That's what Apple did.