This is a crazy-fast (f/1.2!!!) portrait lens. Right now, Nikon doesn't make anything this light-sensitive. F/1.2 lets you basically shoot in the dark--if lighting conditions demanded 1/4 second at f/2.8, you could shoot at 1/25th at f/1.2; amazing!
My 6 Favorite Inexpensive Canon Lenses...I just invested in a new Canon and this will come in handy.