According to Penello, “We don’t support vertical orientation; do it at your own risk […] it wouldn’t be a cooling problem, we just didn’t design the drive for vertical. Because it’s a slot loading drive, we just didn’t design it for both.” We’re not sure how you play your Xbox 360, but Penello revealed that according to their own research, it has been found that about 80% of Xbox 360 owners have their console placed horizontally, so perhaps concerns about it being played vertically might have been overblown.
We guess having it vertical would allow it to be slotted in between items easily, like on a bookshelf or under the television where you might place your DVDs or Blu-ray discs, but in any case if you were hoping to do that with the Xbox One, you have been advised not to.