Users can resize the iPhone apps to fill the iPad's screen, but some elements may look pixelated. It's unclear how many truly original iPad apps exist so far; reports say the device will launch with more than 1,000. But most of these 'new' apps will be updated from the iPhone, and they'll roll out only as fast as they're developed -- and approved by Apple.
On the downside, there's no multitasking for third-party apps, just as there isn't on the iPhone. For example, users can't stream Pandora music while using the Facebook app.