There is really no beating a prime lens for low light photography. Even the fastest zoom lenses are never faster than F2.8 (aside from the two very impressive and very expensive Pro level zooms from Olympus that are F2.0) and such, the best bet for dim rooms and night shots is a real quick prime...
First and foremost, the headline feature of this lens is the exceptionally fast 1.4 aperture; Wide open you will be able to shoot with shutter speeds 4 times faster than even the quick zoom lenses with their 2.8 apertures, The image quality is very good all things considered.
As expected, the lens is a bit soft wide open, the problem is really only apparent however towards the edges; It is however well within acceptable tolerances, The focus on my example back focused by a few millimeters at a distance of about a foot and a half.