Funnily enough I find organic street layouts easier to navigate as a tourist than grid systems. In an organic layout there are central roads that go to places of interest and the smaller streets flow to the central roads. In a grids all the roads look the same (they have the same size for example) so I often can't work out how I'm oriented and wandering around doesn't necessarily lead to anywhere interesting.

I also find grids less satisfying to walk. I feel they favour cars over pedestrians. I'm always stopping for traffic lights in New York while I feel I can walk mostly without interruption in London. London roads are also more interesting because you don't know what's around the corner.

Conclusion: these are pretty graphs but I think the claims in the first post are overstated. Experiments are required.