Something struck me during the initial Windows 8 sessions on Tuesday at BUILD, and I couldn’t put my finger on what it was. Later during Jensen Harris’ wonderful user interface session, as I sat there in the audience using my iPad (yes, with a physical keyboard), I realized what it was. My iPad, sitting there in portrait mode, camera on the top staring me in the face, pointed it out.

Almost everything up on the stage, and shown that day or since, was running in landscape mode, and featured, predominantly, widescreen displays – whether tablet or desktop.

The iPad is, as the Kindle and most ebook readers, “portrait first”. The camera is on the top, the critical home button is on the bottom. Most Android tablets, conversely, have their navigation and camera aligned on the top/bottom edge when in landscape mode (landscape first).

Listening to Jensen’s session, I heard much about what you need to do, what you should do, and what you might want to do. I’m a bit concerned because that story was landscape first. Develop your landscape view, you should do a split view where your app is deemphasized and another app is the principal. And what I seemingly heard was, “and you might want to do a portrait-mode version”, indicating it was optional.

It shouldn’t be.

The prototype device given out by Microsoft to attendees was designed with Microsoft, so I don’t think it is an oversight at all that the device has a “landscape first” orientation.

I’m personally not a fan of landscape being the primary UX, and I’m not alone – Tim Bray agrees with me. Sure, you can rotate it. But at the end of the day, the navigation and camera impact how you will hold and use the device for many tasks, and assume that you will hold it principally in a landscape orientation, and only portrait it when necessary.

I’ve been trying to figure out why Microsoft – the people who almost brought us the Courier design, which was less landscape and more dual-screen portrait – would design it this way.

The only thing I can come up with is Metro itself.

Unlike iOS, which with it’s almost pathetically simplistic (see Windows 3.1) “desktop”, which will gleefully adjust itself regardless of orientation, I’m unclear how well Metro itself adjusts to suit a portrait mode. It is a design that is really all about side-to-side swipes, which runs counter-intuitive to a portrait mode view, as the short strokes across the screen could get frustrating. My concern is that I think portrait mode is an invaluable aspect of tablets – but if the Metro shell of Windows 8 itself almost requires landscape, it’s going to be somewhat frustrating for a user to deal with any apps (chat windows, ebooks, the like) that are more optimally served by a portrait view.

I need to try a Windows 8 tablet myself to validate my thoughts, and unfortunately haven’t been able to. But this is a concern I have that may sound trivial initially, but I think in the end has far more significance and could impact the device’s usability in many consumer scenarios.