It's been just over a week now and I'm finding that I grab the iPhone for quick, on the go and interstitial activities and the iPad for slower, more relaxed and deliberate activities.
The other day I saw some new stories pop up in RSS and actually walked away from my desktop, picked up my iPad, sat back on the sofa, and started reading them there. I've closed my laptop done the same thing. When you have the time and a nice place to sit, nothing beats the iPad experience. When you're pressed for time and need to race to get things done, nothing beats to iPhone convenience. I'm finding the same is true for gaming, social networking, and productivity apps.
What's clear to me at least is that the early cop-outers were wrong -- the iPad isn't a big iPhone or iPod touch and the iPhone and iPod touch clearly aren't small iPads. Just like desktops and laptops run the same technology and certainly have areas of overlap, they also both excel at their own ends of the spectrum (power towards the 12 core vs portability towards the netbook) and have different ideal use cases.
What's your experience been?