I don't think netbook vs. ebook reader is an easy comparision.
It has to bu put in context to work.
How do they compare is all about how one uses them.
Making an analogy: the book -> ebook reader -> netbook paradigm is in many aspects like the film -> DSLR -> iPhone paradigm.
Of course a MF 6x6 camera is a lot heavier than a cellphone.
Of course you can't play Tic Tac Toe with a Nikon D2X.
But photographers going after image quality without compromises still shoot film. Photographers going after the best quality achievable with the digital handiness use Reflex cameras, which are getting every year closer to film quality.
Casual shooters who take a snapshot every now and then use more pratical solutions, like point and shoot or iphones.
But nobody will say that image quality is the same.
Somebody can care not, others can not even see the difference, but it's there.
The same is for reading: the best quality is still on paper (a good printing, I mean, not cheap paperbacks), the best quality with the digital convenience is on dedicated readers (and getting better every year), multi-purpose devices are good if quality is not an issue and for more casual users who need to do a lot of things and good is enough.
I'm in the middle lot: I use a DSLR for photos and a reader for fiction.
Manuals and technical writing on paper.