What are the most common or vicious mistakes when experienced C++ programmers develop in C#?
I've seen many C++ coders code in a COM style in C#, trying to deal with the inadequacies of the language. C# provides lots of a type safe support for your enums and there are usually nicer APIs then P/Invoking back down to C++.
The other thing I've seen catch most people out is that C# generics are not templates.