Designing In Blend
To say that Blend for Visual Studio 2012 is an interactive design tool for XAML misses the power of the product.It’s like comparing Notepad to Visual Studio. In theory, you could get everything done in Notepad, but in reality you would get bogged down almost immediately. Or, as someone once said, “In theory, there is no difference between theory and practice. In practice, there is” (multiple attributions).
Working in Blend is a fluid experience. You can certainly build your pages interactively with the graphically oriented tools, but you can also animate elements, react to state changes, customize templates visually, ...