WPF is easy once you get the general idea of how it works - try "WPF - how and why".
The biggest problem is working out if it is worth it at all and there is still a lot of applications that would be fine implemented as Windows Forms plus a bit of graphics.
I would also agree with the earlier comment about getting into XAML - it's just like a slightly more sophisticated HTML and the only real difficulty is finding out what does what. As for getting stuck later on in a project - don't you always get stuck later on in a project? It is when you start trying to do the 1% that's tough.
