In my area, it's basically replaced newspaper classified ads. So you get people selling cars, furniture, appliances, and miscellaneous stuff that's too big or heavy to ship. Except it's more restrictive, not allowing the sale of animals for instance, which is annoying.

My main problem with it is that it doesn't obey its own filters very well. If I search for "Buick" and set a radius of 40 miles from my location, it might give me a few within that radius but then start giving me a bunch from hundreds of miles away. And it doesn't seem to work outward, but might give me some 500 miles away and then one 50 miles lower down. That makes it less useful than it could be.

It's kind of like Craigslist, targeting local sellers wanting to get rid of things quickly rather than sellers wanting to ship things whereever the highest bidder might be.