The new design feels cumbersome on mobile devices, to the point of being unreadable. This is entirely due to the right-hand sidebar (with the Customize your reddit, Submit a link and Create your own reddit call-out boxes), which appears above the actual page content in mobile layouts. These three boxes are a lot longer than they used to be (especially Customize your reddit), so it takes a lot of scrolling to actually get to the links.

It's great that you can compress the link display, however, without the ability to dispose of the Customize your reddit and other sidebar call-out boxes, reddit is now a pain to read on a mobile device.

For what its worth, that used to be my main means of browsing reddit.

Edit: This is not a threat or anything, but I stopped reading Digg back when their site redesign made it impossible to read on a mobile device. Please don't ignore the mobile device users, though we are a minority to consider when deciding on a layout.