I have this lens and I often leave it on the camera for general use because it is so incredibly good. I haven't seen the article yet but, as Ham suggested, a bokeh comparison would almost certainly result in even more praise. As well as general use, it's also an excellent portrait lens. I was a little disappointed that it was a mainly plastic build, but to be honest this should not detract from it all. It is still built very finely indeed and weather sealed too.

The most unusual thing about this lens is the concave front element. I read somewhere that this is a superior way to construct a lens, but is rarely done due to expense and vulnerability to cracks. Apparently, the smaller 4/3rds format is an advanatge here as a smaller amount/diameter of glass is needed to achieve the same thing. This reduces both costs and vulnerability to cracking making concave lenses a more viable proposition for 4/3rds. Maybe this has something to do with it's great performance and what will probably become known as it's legendary bokeh.

The only other concave lens I know of is the 50mm 1.8 Carl Zeiss Ultron on my Zeiss Ikon Icarex camera and Ivor Matanle mentioned one other somewhere, but I can't remember what it was.