I think the portability has pros and cons. I can see 'whipping it out' due to the instant on etc, in places where you wouldn't be easily able to use a netbook. However, for longer train/plane journies, I think the form factor might work against it. A netbook/laptop will sit there on your seat-back tray and you can watch a movie hands free, or navigate lazily with the trackpad. With the ipad you'll have to support it yourself (or use the ugly Apple case)
I either drive to work, or take a 1.5hour train to another office, or fly 3-5 hours on business. So I don't think it'll fit well with how I travel.
But thats ok, I see enough value as a coffee table/sofa surfer machine to buy day 1 anyway.