I'll try to not bitch anymore about technologies as any of them have good things and bad things after all. I complained a lot about WPF (Windows Presentation Foundation) time ago as I was using it for an application that should have been done using Windows Forms and I think that is not fair. After that I tryed some animation stuff and I found out the actual asset of this technology.
With XAML you can write impressive 3D animations among other cool effects to make your GUI more attractive in some cases. Have a look at this article written by Charles Petzold... very nice, isn't it?
The animation engine is also very powerful and confortable programmatically... say for instance that you want your forms appear fading in, from 100% transparent to 0%. You only need 1 line of code: http://msdn2.microsoft.com/en-us/library/ms590761.aspx
What I think now is that WPF is not ready for business applications where Windows Forms fits really well and has far more maturity and features. I think it has not been designed for that as a priority. WPF is suitable for special GUI applications that require nice effects and maybe in the future it will be ready for any kind of application. As many people say, I see programmers adding weird animations on screens or controls that don't need such a bad user experience, just because it looks cool to them. But that is not a technology problem.
Nobody teaches developers how to desing GUIs and this is REALLY important if you consider the user the most valuable part of the game, as I do. I'll post about that in the future.