With iOS6, when the keyboard appeared, the screen behind it moved up to allow you to type text into the required field. Not any more. With iOS7, the keyboard is bigger and covers the lower half of the screen when it appears, frequently hiding the field you want to type in. Apple have provided scroll up and down buttons above the QWERTY keys to allow you to access different areas of the screen. These are confusing because they look like left or right arrow keys!
We are trying to minimise this nuisance by relocating as much text entry to the top of our screens, where possible. In the end though, we are all just going to have to get used to iOS7.