I use this lens all the time and like it very much. It's been said elsewhere on the forum that it's disappointing, but I disagree. It's not as sharp as the 80mm, but it's not far off either. I'm sure the 50mm-II is better, but I've been very happy with the 50mm-I.
I'm attaching a recent shoot done with the 50. This was shot at f/10, so it might not show as much bokeh as you'd like, but I was fairly close to the talent, so there's definitely focus falloff. Second shot is cropped tighter, so you can see the out-of-focus area closer.
I'll see if I can dig up a shot with less DOF next week.
ethan