Congrads - it's great lens - people like to say that the bokeh on the ASPH is not as nice as with the pre-ASPH 50mm Summilux, but I really think this is a matter of taste, and not better/worse.
The nice thing about this lens is that you can use it at f/1.4 with no reservations whatsoever, and the lens is very flare resistant in my experience. It is expensive, a bit heavy, but if I was only going to have ONE 50mm lens, this would be it. (As it is, I have three 50mms...)
As far as what to expect from f/1.4, well it's just a stop faster than f/2, so it won't be a dramatic difference from what you're usd to, but you will be able to use slower film if you wish, or handhold the camera under dimmer lighting conditions, as well as get a bit shallower depth of field in order to empahsize your subject.
Enjoy the lens, and good luck with your photography.