The interface is engineered directly to the iPad's multitouch screen. Rather than floating palettes, the palettes on the iPad appear to be more of an "on-demand" feature. There's also a specific data-entry keyboard for Numbers, which shows off the flexibility of the multitouch interface.
According to reports so far, it looks much more powerful than a typical iPhone app.
Pages, Numbers, and Keynote cost $9.99 each.
So far there's no information on whether this will be ported to the iPhone/iPod touch.