Boyfriend and I (non-citizen permanent resident and resident alien, respectively) will be traveling through Arizona soon. He will have to get a new copy of his green card to be safe in case for some reason we get checked. I will be right in between visas and might not have my new visa then. This is normally not a problem, but I might very well run into police officers who are not familiar with all the specifics of visa types (I am speaking from experience).
I don't think anyone who is IS a citizen can quite comprehend how stressful these situations can be even for immigrants with legal papers. You make a tiny mistake (a document is missing a signature, for example) and it opens a HUGE can of worms. I understand that people in Arizona are not Nazis, but I would not move there after this law has been passed. Just knowing that I would have to carry my passport and legal documentation around permanently just in case (also because people often assume I am Hispanic when I am in the Southwest).
The law will inconvenience, and probably worse, a lot of legal immigrants in Arizona and is overall just a complete idiocy.