ROX-Filer is one of the more straightforward file managers for Unix. It doesn't try to be a web browser, and doesn't waste resources trying to handle network protocols or virtual filesystems - it expects the system to take care of that. True it its rather RISC OSish roots, it relies heavily on drag and drop rather than the copy and paste paradigm so common under Windows. Users of Mac OS, RISC OS or OS/2 will feel right at home. Although it lacks the three-column browser view of the Mac Finder or NeXTSTEP Workspace Manager, its overall feel is not too far from these, either. It can manage panels, which hold links to frequently-used files and directories, applications and running applets. It can also manage the desktop, handling wallpaper and also providing a pinboard in the style of RISC OS or CDE. You can drag objects to the desktop, but they aren't moved - the icon is just a link to the item in question, like an alias on Mac or a shadow on OS/2. This behavior comes straight from RISC OS.
It uses the GTK2 toolkit, along with the standard XDnD drag and drop protocol. It introduces its own XDS extension to it, but this just allows saving of files by drag and drop. It is not particularly tied to any desktop or window manager, but works better with GNOME or XFCE than with KDE, due to the fact that it uses the same toolkit.