The comparisons with PS4 size (considering that it has an internal PSU too) really shows that Sony has better hardware engineers, they managed to create a smaller console, with internal PSU, packing more power that is cheaper to manufacture. It really is an onslaught in all aspects.
However, I don't think the X1 size is an issue as people say. It has the size of an old VCR, it isn't that big. Unless your console is bulky as a OG XBox or, well, an Atari 7200, everything is cool.