This is a lens which has impressed me more and more I use one. On paper, it's a sharp but over priced lens. But in real world use, it's a fantastic performer. My only gripe is the lack of a tripod collar and it's low magnification at closer focus distances. Other than that, it's superb.
It's also a lens which came in for some really harsh objections when it was first launched. Sure it was expensive, considering most 70-300 lenses were consumer grade zooms. This lens was cut from different cloth, it's a profressional lens and a pretty goon one too. Now it's a few years after it's launch, it's new price has come way down to a far more realistic level. It's still not a cheap lens per-say, but it's good value considering it's strong performance. It's relatively small, light and it's a great range to have.
Personally, I'm holding out for a new 100-400 instead....which is going to be over priced and heavily maligned in the various forums on it's launch....but after a year....it'll come down in price somewhat.