The model tree interface allows for the creation of complex parametric models. The assembly logic allows for very large models to be opened and viewed at the same time. The automation tools are very powerful. The surface tools are incredible - second to none.
There is a very small user base and the automation/scripting tools are poorly documented. The software is no longer being developed and eventually most users will have to switch to CATIA.
If you are considering Digital Project I would recommend you look to Dassault Systems' CATIA instead. Digital Project is no longer being developed and most users will eventually transition to CATIA.
We engineer and construct buildings with complex geometry. In order to do this we create very detailed solid models of all building components and fabricate parts directly from the model. Digital Project (CATIA) makes this possible.