I read about them, and then I drove through one without even realizing it until afterwards. The walls were high enough that I didn't see vehicles to my right, and the crossings were close enough to square that it just felt like a normal intersection of two one-way streets. Once I realized, I actually turned around to go through it again for the novelty and my ADHD brain flipped off and didn't notice it again. I had to turn around again (to continue in my original direction) and that's when I actually paid attention.

I think people find them weird when viewed from above, but when you're going through them there isn't that much to them. If you're in the SF Bay Area and want to try one out, there's one in Manteca, a little more than an hour away.