Should I learn WPF? Is this a good investment of time?

Question

This is my first question here :)

I am a C # developer, not an expert, but still learning and developing. I want to learn WPF to create applications with a good user interface. However, I am afraid that after I spend my time studying this, it will become obsolete, you know, with windows 8 and the metro application, etc., so my question is:

At this point in time, would it be a good time to learn WPF? or am I better off learning Metro?

Thanks.