If we were really looking for a convergence-type device, IMO I do not see anything that the iPad does better that the Notion Ink Adam
http://www.slashgear.com/notion-ink-...ds-on-0969281/that was announced December.
The PRS900 is my first eBook reader and I am very happy with it

I do have a Powerbook and a nano, and I don't really see the iPad replacing any of my existing devices.
I'd wait for a few more months to get some tablet-eReader convergence alternatives to be available, but IMHO, the first gen iPad doesn't make the grade.