Paul – My iPad with Evernote has become my constant companion to my Macbook Pro (yes the 13″ model is the one to have – easy to travel with and loaded with enough horsepower).  Nice and seamless, without any compatibility issues. The rise of iPad magazines will only enhance the value of the device – the Kindle app already offers superb alternative  to the actual Kindle device (although I prefer the Kindle’s screen in daylight).
The iPhone is just a bonus for availability of info and notes when you have no access to your other toys….