I never tried Mudbox. One of the few apps I never tried. People say it is good. I think a Mac version is coming and maybe it works on Wine as well but for a lot of time I was looking specifically at Mac and Linux apps. I've looked at people using Mudbox in tutorials etc and it looked quite straightforward. I have used ZBrush but ZBrush has things like the ZSpheres which are pretty cool and it has a beautiful realtime view which doesn't rely on Open GL shaders. However, 3D Coat is like a revolution especially with this voxel painting. You paint 3D shapes out of thin air with a brush. It's simply incredible but like I say it doesn't end there because it's other tools are brilliant. The only down side is that you definitely need a decent graphics card since it does use Open GL but it makes good use of the Open GL shading.
The guy who develops it is also games designer so that probably figures.
I've messed with modeling for years but was never satisfied probably because I come from a drawing background and poly modeling is very tedious. The only modeling app that interested me, at least for organic modeling, was ZBrush.
So now I can start doing modeling. Instead of dreading the tedium, this 3D Coat totally inspires you. You can doodle in 3D. I've found myself sculpting abstract shapes then suddenly seeing a face of something that I can work on further.
The reason it's bad news for a lot of these big industry standard apps is that people are not going to do any organic modeling or texturing in those apps any more. They have become animation apps. This means that something like Blender suddenly becomes very attractive because it's good for animation. All that's left is a good rendering engine.
An app like Silo is now totally redundant.
What we'll most likely see though is other apps suddenly having to take this on board. Poly modeling characters is now a dead concept. Only the topology afterwards needs sorted.