The arguments over the relative goodness of static vs dynamic typing will continue forever. However one thing is clear: you should use a tool like it was intended and designed to be used. If you want to use C++ most effectively, use it as a statically typed language. C++ is flexible enough that you can (via ptr casts, unions, and #defines) make it 'look' like Smalltalk.
There are places where ptr casts and unions are necessary and even wholesome, but they should be used carefully and sparingly. A ptr cast tells the compiler to believe you. It effectively suspends the normal type checking facilities. An incorrect ptr cast might corrupt your heap, scribble into memory owned by other objects, call nonexistent methods, and cause general failures. It's not a pretty sight. If you avoid these and related constructs, you can make your C++ code both safer and faster -- anything that can be checked at compile time is something that doesn't have to be done at run-time, one 'pro' of strong typing.
Even if you're in love with weak typing, please consider using C++ as a strongly typed OOPL, or else please consider using another language that better supports your desire to defer typing decisions to run-time. Since C++ performs 100% type checking decisions at compile time, there is *no* built-in mechanism to do *any* type checking at run-time; if you use C++ as a weakly typed OOPL, you put your life in your own hands.
