Geo can be directly download from Carbon Graphics website, then you will need to apply to get an evaluation license to unlock Geo. After starting Geo, the Geo desktop appears.
Well, actually the screenshot tells a lot. A tree hierarchy, a 3d view, a toolbar with icons and objects properties panel on the rightside. But here are some sidenotes: the edit box at the bottom of the window works very much like in Maya or Max, allowing you to type in scripting commands or access the scripting window. This comes in handy when you are familiar with GeoScript. Unlike Creator, Geo uses a vertical tree view of the scenegraph hierarchy, which we think is not as capable as the horizontal hierarchy view. On the other hand it is the good old tree view, everybody is familiar with, and allows right mouse button operatons in the menu. The rightside toolbar allows direct access to the selected nodes properties. We have found this approach better then the floating window of Creator as editing the properties of a node is a part of everyday modeling.
In general we have found the GUI design to be quite intuitive, it is definitely designed for realtime modeling for OpenGL based image generators and provides quick access to the attributes of polygons, textures and colors. One thing which is not that nice is that Geo used all the CPU power on our Windows PC unless its window is minimized. Even when the Geo window is under other application windows, Geo uses the CPU. Not very nice when switching between your texture editor and Geo all the time.
Note: Andy Bushnell has reacted quite fast and fixed this after we have reported the problem.