So what do you think?
In terms of sharpness, it definitely delivers - corner to corner, wide open. Much better than the 17-40 and 16-35 2.8II that I owned previously. Can't say too much in how it renders colors and contrast since it was such a gray day yesterday. I want to see how it handles flare.
In terms of handling, it is well built yet light. Balances well on the camera. Feels a lot like the 100mm L in those respects. The IS is most certainly a nice feature to have. Looking forward to shooting more tests today. At least the sun is shining!