I have been using Rhinoceros 3.0 now for over a year. It is an incredible piece of software with capabilities that allow you to work in 3D space with relative ease.
In an nutshell: if you need reasonably-priced software that allows you to work well beyond the limits of standard 3D CAD programs, then look no further.
For months I researched quite a number of high-end and low-end 3D CAD programs trying to find one that could work with a complex twisty-curved surface of a special CAM drive. In all cases, no other program came very close to being able to create it. I asked the CAD company experts for help. All tried, and failed. You see, other CAD programs were designed for the standard machinist using standard construction materials, and they do that very well (and with some pretty disgusting price tags). Then I came across Rhinoceros, and in 10 minutes had created my complex surface without training, and with incredible accuracy. To make matters even better, the price tag was considerably below the other CAD program prices.
Since then, I have driven Rhinoceros 3.0 from an external Visual Basic program and used Rhinoceros as a 3D graphic engine (very cool). Some of my work requires design of complex Super-computer cases. I have parameterized the process, so generation of a new case with totally different requirements takes less than a minute, creating multiple surface solids, complicated metal snaps, extrusions, and other parts such as complicated plastic handles and bezels with counter-sinks and precision holes of various dimensions. Within 5 days, my plastic parts were manufactured at Proto-Mold and returned exactly as designed, and other vendors created precision steel, aluminum and brass parts from Rhinoceros export files.
Visual picture files depicting photo-realistic images using Rhino's Flamingo renderer brought millions of investment capital dollars into our company, thus allowing us to build the real items.
Rhinoceros has many ways to accomplish the same result, so you can choose what works for you best. I have created geodesic domes, pleasant shapes for relaxation, and other things just for fun. I have recently purchased a CNC Milling machine that I now drive with Rhinoceros 3.0, RhinoCAM Pro (Visual Mill 5), and MACH3 CAM driver. So far I have created tools, cut fan cutouts and switch cutouts in aluminum panels, and general machining and polishing. I intend to make molds for plastic and concrete, and design and build an engine extraordinaire. The sky (and your imagination) is the limit. You are only as good as your tools, and Rhinoceros tops my list of creative enabling software. It is an incredible bang for the buck, and the only program that can do what I require.
A Final Note: This is a complex piece of software, yet the basics are simple to learn and fun to work with. You can use as much or as little of its power as you desire. But as with any complicated piece of software, there are difficult situations that you can encounter, and some things that Rhinoceros is not exceptionally good at, requiring some extra effort to accomplish. So far I have not found any show-stoppers that I couldn't find a work-around. Also, the staff at McNeal Associates were pleasant and helpfull with good response time to difficult issues. All in all, an excelent value and an excelent piece of imagination-expanding software with good support. I highly reccomend it.