If you are referring to Soft Typing parts, I have some experience with it. They are useful if you want to have different part types with different sets of attributes, initialization rules, icons, lifecycles, access right rules, version schemas and workflows. The kicker is that once created of a certain type, there is not "supported" way of changing the type. Not easily that is. So its up to the end user to get it right and right the first time.
When we started using Windchill, we created soft types for parts and docs. We ran into maintenance issues like I illustrated above requiring lots of admin fixing. Since then we reduced the use of soft types and used PartsLink to handle the various part types. Most of what we wanted was unique attribute sets. Since PartsLink allows for things to be classified at any point, easy to fix errors. Short answer, walk careful into this and if you can avoid the complexity, do so.
