You shouldn't notice much. The build will take time, Sprint will operate Mobile WiMax and LTE In conjunction for a while, slowly migrating people to LTE modems and smartphones.
Most people replace their smartphones every couple years anyway. So even if you pop for a Sprint Wimax phone now, you can switch to an LTE smartphone in 2 yrs when Sprint will be getting LTE coverage everywhere. -- Record your speedtest.net results in DSLReports SpeedWave »www.speedtest.net/wave/1b3ef29fa84ff7ce