It's my impression that many are disappointed by the iPad. I think this is because, as digital professionals, we were hoping for something we could use as we perform our craft. Something that would let us leave our laptops at home. Sorry, but we're not Apple's target demographic.
In my analysis I'm going to divide all computer usage into two categories: production (of media) vs consumption (of media). We're producers -- and Apple sees a much bigger market among the consumers.
As a device for media production, the iPhone can claim points for producing tweets, and photo streams for flickr, and a few fingerpaintings, but that's about it -- in my production/consumption dichotomy for digital media, smartphones sit heavily on the consumption side of the fence (but aren't very good at it, really). Furthermore, the market for digital consumption is only getting started. Devices like the Kindle, Apple TV, and digital picture frames are still niche products; most of us buy printed books and magazines, and print our pictures on paper when we want to frame them.
Truth be told, many home laptops and desktop computers also sit heavily on the consumption side of the fence. That's why I think the potential for the iPad is very large. If the iPad can provide the best available experience for online media consumption, and I'm prepared to think it can, then how can it fail to do well?
On the other hand, whether or not the iPad will prove to be a compelling tool for media creation is an open and fascinating question. I predict success for working with photos and photo collections, playing with and performing music, and hopefully drawing. I also imagine we will find ways to repurpose the iPad (and its descendants) as an interesting input device to "real" computers. But I don't expect to need one for my work as a software developer any time soon (unless I decide to write iPad software, of course).
Before closing I have to mention that the way that Apple has positioned itself as a tollkeeper, charging for access to this media, and censoring content that harms its business model, is certainly annoying. I would really love to see someone rise up and offer compelling alternatives to the iPhone and iPad, but so far (and I speak as an Android phone owner) I am disappointed. As a potential application developer, fixing the problems in Android is beyond the scope of what I can do for my users. Google just doesn't seem to understand what's required to provide the same quality of experience that Apple gives its users. Must the freedom Google offers come at such a price?