With a height of 45px and corner rounding of 5px, I’d be expecting the iPhone rendering. Which were you expecting/wanting? If the fully round ends, try increasing the border radius to 23px or more.
My iphone emulator shows no change to the button with border-radius so you will need to remove all styling and style it from scratch. You can use the prefix -webkit-appearance: none to remove the styling and then restyle it as you want it.
Another anomaly (in the emulator anyway) is that box-shadow on the input only works if you use the prefix -webkit (the emulator is running ios 4.3 and ios5 doesn’t need the prefix).