I've been using the Apple Wireless Keyboard for a couple of weeks now. The hardest thing to get used to was not being able to use keyboard shortcuts for things like cutting, copying or pasting. It feels funny lifting my hands from the keyboard and touching the screen to copy, then returning to the keyboard again... but I eventually got used to it.
It's a little annoying that when the keyboard is connected, the soft keyboard on the iPad is no longer accessible. There are those times when it would be nice to pick up the device and quickly tap something into it, before going back the keyboard.
To conserve battery power, you should turn the keyboard off. Because the light on the keyboard only lights up when you first turn it on (after which it goes off), it's difficult to know precisely when the keyboard is actually on or off. The best way I found to do this is to look at the Bluetooth icon on the iPad instead. If the icon is faded, the keyboard is off. Otherwise, the keyboard is on.