I found this component very easy to install and configure. You can use a simple, single layer category scheme and run a "Craigslist"-like site or you can create several layers of categories and subcategories. Once you get the hang of things, this is a very powerful classified ads system that will accept a fair amount of customization.
The only glitch I could find is its inability to upload PNG files via the new ad submissions form. I suppose there's a fix, but copped out and simply changed the appropriate language file entry accordingly, with JPG and GIF uploads being good enough for me.