Scrolling is exhausting — it never ends. There is no sense of accomplishment. I once heard someone refer to infinite scrolling on websites as “a game you can never win.”
I prefer pagination for a different reason. With scrolling, I feel like I have too much control. I constantly have to “measure” how far to scroll and make the proper precise movement. My eyes have to track the content as it moves. It’s exhausting because of the concentration it requires compared with just pressing a button and having the right thing happen.
Update (2012-11-01): Lukas Mathis:
If I’m reading a novel, the experience I’m having should be the book’s story unfolding in my head, not my fingers scrolling the page every few seconds. In this case, good UX design means not interfering with the actual experience the user is having: the book’s story.
Look at iOS’s home screen. There are pages of apps. You jump between pages, you don’t scroll. Is the home screen’s pagination an artifact of paper book technology, or is it simply a better idea than having a home screen that can be scrolled? I’d argue that it’s a better idea.