I've had this lens for about 24 hours, and have popped off about 500 shots with it. It's great. I had the 17-70 2.8-4.5 - but found that I was getting frustrated with the loss of a stop & third at the long end. Traded it in at Henry's for half back towards this one.
Bokeh at 50mm is nice, low light performance is great too.
Hunts for focus in very low-light -=- but then again, I can't see that great at night either -- why expect the lens to change that ;-)
So far - My images have been SUPER crisp. I'm extremely satisfied.