Overall, I really have been blown away by this lens.
While not entirely flawless, it is certainly one of the best general purpose lenses I have ever owned or used. The only faults I can sight are the fact that there is some "moustache" distortion at 24mm and that the IS takes a second or so to function effectively. Other than that, the lens is gold.
The sharpness wide open blew me away from day-one. My first test shots of some pepsi cans wide open at various FLs actually produced moire on the fine print of the can. When observing portraits wide open at 100%, the amount of detail rendered in the focal plane is simply stunning. AND, the bokeh is pretty good. Maybe not 135mm f/2 good, but still very nice.
The colour and contrast are exceptional, the focal range is ideal (for me), the focus is fast and reliable, the lens is sealed and very well built. What more can I say? Excellent, excellent lens.