I bought this lens for available light shooting at indoor events (theatres, churches). It's amazing. Excellent image quality. Beautiful bokeh.
I find the Electronic Manual Focussing akward to use but that may just be me. Wide open the lens requires extremely careful focussing: depth of field is paperthin at f1.2 and shorter distances. Autofocus is relatively slow but that hasn't bodered me much. Just don't bring it to shoot a basketbal game.