I'm tired of the comparison to the iPod or the iPhone. The iPhone had tons of innovations on day 1. The iPod had some innovations to begin with (your music library in your pocket), but other key ones -like the click wheel and the iTunes store- came later. The iPad doesn't really have anything innovative in it today.
Yes Apple may add more innovations later, and it may succeed even without them (coz of iPhone users moving up, Apple's brand & marketing, etc.) but the 'Apple will succeed because the iPod+iPhone did' argument is getting old.
I absolutely believe in a simpler less-general-purpose device for casual home computing, and a lightweight tablet seems like one of the top contenders for the form factor, but the iPad itself is a pretty weak product.