For most web developers, the compelling feature is the ability to rapidly create forms. The key advantage of ToscaWidgets over other forms libraries (e.g. FormAlchemy) is the ability to use complex widgets. More advanced developers will want to create their own widgets, to promote code reuse.
TurboGears pioneered the concept of widgets in Python web frameworks. This turned out to be a very powerful feature, useful beyond just TurboGears applications. ToscaWidgets aims to be a standalone widgets system, independent of any particular web framework. The API was originally quite similar to TurboGears widgets, but has diverged over time. TurboGears widgets are now legacy and included in TurboGears 1 for backwards compatibility only.
A major criticism of ToscaWidgets early in its life was the lack of documentation. There has been considerable work to improve this situation, and it’s now believed that adequate documentation exists. Feedback is always welcomed, and if you need further assistance, please ask on the mailing list.