Bought used (3 months old and immaculate) it's just arrived. It's a cold foggy dismal kind of November day but I went out at lunchtime to try it out... well you would wouldn't you?
As I'm using a 20D it's instant result time and the end product is simply amazing. Sharpness, colour and contrast are outstanding, and it just walks all over my Canon zoom lenses, one of which cost over twice the price of this. A quick tweak of levels in photoshop and it got even better! So what that I don't have IS and it's not as versatile in many ways, but... it's faster and sharper and way way better.
If you need a lens of this focal length, and I suppose if you're reading this you quite probably do, then you'll go a long way before you find anything better.