i don't know, man... Doing work on a PC, answering e-mail, surfing the Net, etc. is totally different than reading a book. Working on a PC already is known to cause eye strain. I work in front on a computer all day, and i need to take breaks to help with eye strain. No way would i read books off the thing.
That eInk technology in the standard eReaders really does help. I have read some books on my sister-in-law's Kindle and it really is just like reading a book. My eyes didn't feel strained at all.
I agree that the iBooks app is slick as far as the buying/choosing books.
now this magazine stuff looks cool on the iPad:
http://www.youtube.com/watch?v=ntyXvLnxyXk