frank I didn't like the first version of mudbox but the latest one is really impressive at least in the feature list. the comment about the autodesk product is irrelevant I mean I was a lightwave user and I switch to maya. I didn't feel the lack of stability. Also modo crashes a lot and it don't work on low end computer but Maya does ( athlon 3200 geforce 6100 for example).
Mudbox 2009 has a lot of painting tool and it's really impressive. You should really look at it at least to compare them with actual tool. But I do understand that the price is high for a non complete package.