For using the phone version on a tablet in landscape mode, the text shows up in white on white background rectangular box and the keyboard takes up a little over half the screen. If you type in portrait mode, what you type shows up normally and you can see what you're typing directly onto the screen (whether it's in a mail app or a browser, etc.).
With the tablet version in landscape mode, you can actually see the top half of the screen area where you are typing into.
SwiftKey is leaps and bounds better than any other keyboard I've used for my Nexus 7.