If you couldn't stand with Carrara 3 may be you will have also difficulties with Truespace.I have both and ,according to me ,the learning curve of Truespace is more difficult than the Carrara one.All 3d programs have there difficulties and bugs. You must work and work with them.May be you will be better to try some free ones like Wings.Zbrush is really fantastic one:i am still stuggle with the interface and the zspheres.The more easy one i have used is Rhino3,a nurbs modelling one ,even i use may be 30 % of its possibilities.I also like the Vue pro interface(Vue is one of my preferred program) but it isn't a 3d modelling soft.Good luck!