So why would you want to use wxPython over just C++ and wxWidgets? Personally I prefer using Python for everything. I only use C++ when I absolutely have to eke more performance out of an algorithm, and even then I usually code it as an extension module and leave the majority of the program in Python.
Another good thing to use wxPython for is quick prototyping of your wxWidgets apps. With C++ you have to continuously go though the edit-compile-link-run cycle, which can be quite time consuming. With Python it is only an edit-run cycle. You can easily build an application in a few hours with Python that would normally take a few days or longer with C++. Converting a wxPython app to a C++/wxWidgets app should be a straight forward task.