I think they're suggesting a subconscious perception of the subtle differences in sizes that result from building with round numbers in metric vs imperial (e.g. 1 meter is different than 3 feet). This is interesting, but seems less likely than the more dramatic differences in architectural styles, materials, regulations, and zoning.

Paper sizes might be a better example of this since the only difference is the dimensions. Something about the relative dimensions of A4 paper just looks nicer to me.

(I know the ISO sizes are based on the golden ratio, but I think this probably has more to do with me being a lawyer practicing in the United States. PerhapsUS-Letter and Legal sizes subconsciously read as "work" to me and A4 reads as exotic.)

  > the ISO sizes are based on the golden ratio

No, 1:√2. (A golden rectangle divides into a golden rectangle plus a square; an ISO rectangle divides into two ISO rectangles.)

I meant to scope in my question more. Does it feel like houses are too tall/short, narrow/wide? I can understand that there would be differences, but I would be surprised to know that they were noticeable.

And again, it would not be limited to just US houses, would it? Specifically, are most buildings in older EU cities built to metric specifications?

The proportions and standard lengths are all slightly different. For example, standard US fences are 3 feet high, but standard EU fences are 1 meter high. This is a noticeable, but not striking difference.

It's like using letter paper format instead of A4, it also feels a little odd to me.