Not really the same at all...
I think likening the iPad to early CD-ROM multimedia PCs is akin to comparing a modern paperback to a book hand written and illuminated by Monks.
VGA resolutions on large clunky CRT displays and underpowered PCs were never going to change the way we read. The content may not be terribly different to that envisaged for the iPad, but the method of delivery is light years ahead.
Similarly, while I could go to the local cathedral to have a look at some of their chained books, it's not very convenient. Or cheap (in terms of getting the content into a readable form -- those early multimedia PCs weren't cheap either). Paperbacks, on the other hand, are pretty cheap, easily portable, can be produced quickly and easily in vast numbers. Even though the actual content is largely the same as the handwritten book.
Accessing interactive books via an iPad, however, is convenient, and can be cheap (hopefully the publishers won't get all greedy on us).
The printed word didn't take off until it could be reproduced and distributed cheaply (thanks Gutenberg and Caxton), and the population sufficiently literate. Similarly, multimedia in this form (and eBooks in general) will not take off until they can be reproduced and distributed cheaply and easily; and the population is sufficiently (technology) literate.