It is excellent in generating tool-path solutions. The "between curves" and "boundary" options are excellent in calculating partial area solutions. The fact that the tool-paths can be modified using Rhino is a definite plus. However, the documentation is very lacking. While using it error descriptions are sometimes not helpful in identifying the issue. It therefore requires a larger than usual trial and error to discover a solution.
I'm a musical instrument maker, and have recently started using Rhino to design instruments. I've been using Vectric VCarve Pro for 2 and 2.5d work, and it works very well. But I needed a 3D CAM solution that would keep my X and Y origins at the same place as my Rhino models (this lets me use some of the same indexing jigs that I use with VCarve without a lot of fiddling around). I also needed a CAM solution that would allow engraving along a curve.
To make a long story short, I downloaded trial versions of several CAM solutions within my price range, and MadCAM came out on top easily. I've been using it now for several weeks, and I've found it very intuitive to use, and the toolpaths it has generated work very well on my CNC machine. The few questions I've had have been quickly answered by the MadCAM folks. Rhino and MadCAM make a very powerful combination for musical instrument makers.
I am a Mechanical Engineer, so have extensive CAD experience but have never used a CAM program before. madCAM is my first. I did demo about 10 different programs before choosing, and madCAM had the best combination of ease-of-use, powerful features, and reasonable price. Knowing Rhino3D (since it only runs as a plug-in) is a big help but not required.