The whole system sucked. Those things has little memory or CPU. Windows Mobile didn't have memory protections or preemptive multitasking. Pocket Internet Explorer sucked even worse than Internet Explorer 6. It was challenging to find apps for them.

But the real disruption was the disruption in the carrier relationship. A lot of smartphones didn't have WiFi, and the carriers would nickel and dime you for every kilobyte. Apple convinced them to do the flat rates and big chunks of data. Apple introduced manufacturer control of the user experience, instead of Verizon disabling every feature that would allow you to avoid the carrier's fees. When the iPhone was announced, the feature I was most impressed by was the visual voicemail. Voicemail was so tedious and inefficient before iPhone.

(That was the point)