You may know that I switched from the Canon 5D MKIII to the Lumix GH4 last year. Since I made more than enough on the sale of all my Canon gear to completely switch systems, I wasn't really planning to expand on my lens collection anytime soon (already had four pro lenses from Lumix and Leica).
But the word on the street regarding the Leica 42.5mm 1.2 Nocticron has been beyond compare. At $1,500 it is the most expensive lens available for the Micro 4/3 systems, and worth every penny. The Bokeh (background blur), sharpness and low light capability are superior to any of the Canon L series lenses I have owned, some of which cost twice as much.
The attached photo was shot handheld, in ambient light, and at 10 feet away, I was still able to control the depth of field so precisely as to blur the Bride's arm in the foreground, and her Son's face in the background. No post processing required.