I've been using geOShell for a couple months now, and it's phenomenally different than any other shell that I have seen, most definitely the standard Explorer.
The entire setup is based on geObars - small little things that are always-on-top (usually), usually go up against an edge of the screen, and can have one or more plugins in them. This means that applications take up the entire screen without interfering at all with the shell's functionality, and the shell rarely interferes with programs.
The plugins both replicate functions found in Explorer and add new ones. The basic, important ones are the system tray, taskbar (it's a very small program switcher which uses icons and no text), and quicklaunch (known as geOFlexiMenu). The clock is in a plugin which changes to a run dialog when you click on it. There are no desktop icons in standard geOShell, but they can be added with a plugin.
Some of the functions from Explorer are replicated in a menu which appears when you right click on the desktop. This allows you to get to drive letters, the start menu, the control panel, and desktop icons, along with shutdown, log off, and recycling geOShell (restarting geOShell to fix any momentary bugs that have occured).
One thing to note is how efficient geOShell is with certain multi-monitor systems. If one of the monitors doesn't have windows covering all of it, that makes it much easier to get to the right-click menu discussed earlier.
Because geOFleximenu is a confusing plugin, which requires registry editing to work, here's the link for the geOShell page regarding it: http://www.geoshellx.com/userguide.asp?doc=plugin.geofleximenu.inc