Really?!

I have no reason to doubt that information and I am happy to believe you especially if you have used one of those but I find it rather unexpected, if not downright shocking. All the pics I have seen are in landscape. There is a fixed keyboard attached permanently too the device. On hinges, not a slider, hence no way to turn the screen to portrait without a keyboard sticking awkwardly to the side. And finally, although I believe that Windows can be used in portrait, it would not be my first choice. "Natively portrait" is not what I would expect.