I bought this lens to use as my midrange zoom. I have the Sigma 28-70mm f/2.8 already, but found myself needing that extra 4mm when shooting with my D70.
Overall, I think this lens is a good value, particularly if you can find one used. It exhibits a slightly warm, pleasing color balance and very smooth bokeh. The AF is smoother and faster than my 28-70. It also has reasonable build quality for the price. It works very well as an indoor wedding lens, as the slight softness and nice color balance can produce very flattering portraits.
However, compared to the 28-70mm f/2.8, this lens is very soft. Also, its contrast is much lower than any of my other lenses. While it works well as a portrait/candid lens due to the flattering color and softness, I would not recommend it as a general-purpose, as the 28-70mm has MUCH higher contrast and sharpness, and is slightly cheaper. Also, as everyone else has mentioned, it's a BEAST, and 82mm filters don't come cheap!
Given the choce, I would recommend the 28-70 over this model, despite the shorter reach...