Our local 3D printing shop likes MeshMixer, so I decided to give it a try. A new version of MeshMixer was just made available about a week ago.

AutoDesk is trying to position MeshMixer (MM) as the single application that you will need to create 3D models, modify 3D models, and prepare 3D models for printing (including fixing 3D geometry, generating support, etc). They print via the Win 8.1 3D printing facility, which is not available for very many printers yet.

I found the MM UI to be almost impossible to understand without studying their documentation. And their documentation is old and spotty. The YouTube videos seem to be 2 years old, which does not bode well for a product that is a week old. While some of the program features worked (I was able to sculpt the bunny a little bit), many features did not work at all for me (the flatten and spike brushes). No idea what Shaders are, but when I clicked that and then selected a Shader, just about nothing useful happened thereafter. Not at all intuitive, and not at all amenable to learning by poking around.

MM managed to generate interesting support structures, and that by itself might make it worth learning (at least in that small aspect of the program). You can import an STL file, generate support, and then export to another STL file.

I imagine that if you are used to using MeshMixer, it feels as if it is intuitive, but it certainly is not that way for me. It is free, so give it a whirl if you have the time. But you can expect a lot of frustration.