The thing about the "death of printing" that's been talked up so much ever since computers were cheap enough to own... Well, a few things.
One, it hasn't happened yet (not a strong argument, obviously)
Two, it won't for a while - it'll be years before people can buy something to tide them over on a plane ride and have it be reading material and digital at the same time. Sadly, a great proportion of reading happens like that - people run somewhere to buy a book for a trip. I'm an English major, this depresses me.
Three, digital reading doesn't have the tactile "now" feeling of a printed product. Comic books and other printed materials create, to translate some literary theory stuff into terms I can hold in my head this late, a little circle. That is, you start at your head, go down your right arm (or your left, if you're cool - and left-handed), hit the comic, and go back up the opposite arm to the head again. It's actually good to think of this as a field the reader is making. Within this field, and almost the whole body is in here, it's all about the reader and the text.
Four, related to three, the actual reading changes. In writing comic scripts, I've had to learn to remember when the page is turned, when the reader can see something, even though it hasn't "happened" yet, and how to deal with all this. Simply, big reveals go on the left-hand pages - the page that's hidden until the moment you're reading it. This isn't always true, but it's a great simple "rule" to keep in mind. Using the computer, this kind of thing doesn't work anymore. True, with some comics (like QC here) the page length creates the tension. You have to scroll. Some people, however, refuse to read comics where you have to scroll. It's often cited as a design thing, that the content page should be contained in the window without scrolling. That's a bit silly for comics, but a good idea for something like a search engine or a portal. Also, reading at the computer removes the sense of absorption. Even if you don't multitask while reading online comics, you know you *can*, and that the tool you're sitting before can do many more things. I check most of my webcomics while eating breakfast, something I can't do while checking out the latest issue of Battle Pope.
Damn, this is long. Can you tell I'm in a class about graphic novels?
Oh, and the thing about "words on a printed page" versus comics? I think someone made a more interesting version of the "apples and oranges" analogy already. Yeah, exactly. Comics provide more immediacy, but rely on that. A novel (or short story, short-short, poem) has the luxury of building, letting the language itself construct everything. Of course, prose relies on that. You don't get much in the way of "gut-punches," as you could call the immediate, emotional slams a comic can deliver. Comics don't really give a reader the kind of chilling, filling atmosphere prose writing can, because there's just less to move through - each word in a well-written prose piece contributes to what Poe called the "singularity of effect."