I was taught QuarkXpress in college but have recently switched over to InDesign. I attended a design seminar a few weeks ago and it seemed like 75% of the people that had recently switched over.
I'm using it to design a photography book I'm publishing and am impressed with how intuitive it is. If you know QuarkXpress, you know InDesign. And being an Adobe product, it works nicely with Photoshop.
I'd love to see some design samples from anyone out there who's used it for publishing. Here's a simple CD cover I designed for a local country artist using Photoshop and InDesign.
CD Cover