At f1.4 the lens is rather soft, but since it's wide open, everything will be looking creamy anyways. It's a nice effect, except of course when you want things sharp. Stop down to f1.8 or 2.0 and you'll be sitting pretty.
Congrats, it's a fantastic lens, and I only wished I hadn't upgraded to full-frame and could keep the lens.
Hmm, I got mine a day early (Thanks UPS!) and I'm wondering if I got a bum copy. At F1.8 or higher it looks nice & purty. At anything lower I'm getting some nice halos on my images. Here is one sample, shot at 1/1250 @ f1.4 on my D200