Introduction to Double Exposure

Looking at some other's work, I find it pretty easy to compare myself to what I may be missing. And today, I discovered why I deserve to feel bad about missing out. 

I've owned the Canon 5D Mark III for about 3 years now. And just found out about the Double Exposure feature and how I can creatively use it to make fine art photos in-camera. I'm a loser. 

I watched this video tutorial, and tried this in all of about 10 minutes in my hotel room. What do you think.