iPad is really good at doing what it's designed to do, and really bad otherwise. It's not a satisfy all device, as we've seen in the response to it so far.
Really? What the fuck was it supposed to be really good at doing? Running the iphone OS?
A lot of tech nerds don't understand just how unnecessarily complex computers are today. Watch a 60 year old try and use a PC for the first time and you'll realise how non-intuitive the modern desktop OS is today.
The iPhone OS moves away from antiquated input devices (mice and keyboards with cursor keys and function buttons) and towards a touch interface that is simple and intuitive.
The other benefit is the sandboxed limited nature of the native apps. The average user is tired of having to do a clean wipe of their computer every couple of years because the software they've installed has slowed down the OS. I think that in the future, apps won't be allowed to make changes to the underlying OS. If you want to do something complicated, you'll need offload your app to the cloud.