9 out of 10 points and recommendedSharpness, flexibility, wide zoom range, build, color, contrastWeight, price, softness at f/22 and up
I read a lot of reviews of this lens before I decided to buy it. Typical criticisms were softness, slow AF, and the zoom mechanism. One of the things that became apparent after all those reviews was that it seemed that the newer copies were better. So despite the fact that I could have saved money by buying a used one on Ebay, I decided to buy a new one to insure I was getting a recent copy. What I got was one that was made in October of 2008. I was pleasantly surprised to find that it was very sharp across the focal length range from wide open up through f/16. There is a very noticeable softness at f/22 and above but since I rarely use that aperture range, I'm not too concerned. Where it is sharp, it's only slightly softer than my 70-200mm f/4 IS and a 135mm f/2 which are both about as sharp as they get. As for the AF criticisms, this one is fast. The IS gives at least 2 f-stops, maybe 3. Maybe the biggest challenge to the IS is the weight of the lens. It's heavy. I'm sure if I use it regularly, I'll bulk up and it will be easier. :-) One thing I've already found out, it's not easy to hold steady in a strong wind.reviewed March 27th, 2009 (purchased for $1,465)
Despite all that, I really like it. I've already been able to catch birds in flight much better than I could with other lenses. Some people don't seem to like the push-pull and it clearly takes getting used to but I think it's faster than most twist zooms if you have to zoom very far, very fast. It also isn't hard to adjust the zoom tension so that it doesn't creep but is still reasonably easy to move. Having said that, if you know you're going to need to zoom fast, it's best to loosen it ahead of time. The adjustment works well though except for the often criticized conflict with the focus ring which is justified.
All in all it is a very flexible lens and I recommend that you try it if you're on the bubble as I was. I do recommend you get a recent copy whether new or used. The other big con is the price. Going rates for used ones do not justify getting an old one that isn't sharp. Except for the price, I would have given it a 10. Oh yes, don't drop it on your foot. ;-)
Here's a couple of uncropped examples: