So I've had the iPad over a week now and have observed how I (& others) use it. It is definitely a content consumption device rather than a content creation device. I can answer emails on it and I'm writing this blog post on it with no problem - I quite like its virtual keyboard. But, 99% of what I use it for is consumption. I've finished two books on the iBook reader and enjoyed them. I've used the iBook reader for PDFs of academic papers just fine as well. The zinio magazine app is great and magazines are really readable. Movies & TV shows & TED talks are great on it along with social media apps like TweetDeck.
It doesn't replace my laptop for what it is good for (content creation) but it has for consumption on the sofa or at a café table.