I frequently use it to search (and reverse-search) products, specifically modern interior design objects. Often things show up in blog feeds or on Instagram where it's been reblogged from some source, and I want the original page that describes what it is. Or I use image search by text to try to identify pieces that I can describe in words ("leather bauhaus lounge rocker 60s chrome" or whatever).

Many other use cases. "iPhone case" -> browse cases, see one you like, find the page where it's sold (effectively a federated shopping search). Or "New England bed and breakfast" as a way to find somewhere cute to travel.

I often use Google Images to find actual articles to read. It happens like this: I search for a combo I'm looking for, only the pages that Google finds are not exactly about what I'm after. From the images I can see immediately if the article at least contains some relevant information for me.

Sometimes I do, usually when I want to find a teardown or repair information for a piece of hardware. Image results often let me determine more quickly which pages contain a good teardown because they contain quality images of the inside of the device.

I mostly use it to get links to the originals of images people post on Facebook, so I can share them further without linking to FB. I guess that makes me a dirty pirate stealing FB's ad revenue...