Visual Studio is one of the best friends for the computational designer, providing a user-friendly programming environment.
Although it is rather easy to create a .NET script inside Grasshopper, it is almost impossible to produce a larger and more complex one without a proper editor. VS also provides a debugger, very handy to seek code issues. McNeel provided a free Grasshopper and Rhino assembly for VS to help newcomers understand their code structure. You can find them here.