the 16-35L II was my most used short lens before getting the 24-70L II but i have to say that the 24-70LII is pretty much welded to my camera now. the 24-70L II + 5d III is a sweet combination. the combo really has brought the excitement back for me!
anyhow back to the 16-35L II -- it is the only lens i own that i will shoot wide open only if i have no other choice. i consider f3.2 wide open on that lens. but it still is very good and UWs tend to look sharper anyway.
The 16-35 II is one of the few I have yet to actually own at some point... I have used the 17-40 before (and I just bought one which comes tomorrow), and it is a good lens for the money. I have read mixed stuff on the 16-35 being worthwhile if you don't need the f/2.8, so I had a hard time spending for it. Especially with the 24-70 II for f/2.8...
What do you think of the great 17-40 vs. 16-35 II debate, putting aside the f/2.8 vs. f/4? IQ only.

