I have the 16-35mm f/2.8, and I am happy with it. I use the f/2.8 far more than the 35-40mm range, plus the faster shutter at other apertures...
Now a 16-40mm f/2.8 or a 17-50mm f/2.8 IS would be perfect...
The day they announce this lens is the day I put my 17-40 up on craigslist and put my order in for this one. The irony with the price inflation over the last year, the price I paid 2-3 years ago for it new is $150 cheaper than current retail rates so I could make up my entire investment on this lens and then some on the used market. =) It's not often you need shallow DOF (F 2.8 ) for wide angle because bokeh is diminished in wide angles due to the wider angle and lower focus scale making the relation between the subject matter and infinity a lot closer than mid range or telephoto. If I need that tad bit of speed, I will throw in my 430 and give me my extra light.
Now what I want and need is that a lens that is sharp, sharp, and sharp. Corner sharpness doesn't have to be exceptional, acceptable even on full frame, and an IS that does a good 4 stop correction. I shoot a lot of architecture and commercial real estate in which I go into a lot of empty warehouses or foreclosed buildings and have to take pictures quickly with what I'm given as I'm paid by the job, not the hour, so If i spend a day or an hour, I still get the same pay. If I can handhold close to a second and get sharp photos, I'll buy 2 of them.
