Last July, I bought a new one for $1350 on a impulse buy from Newegg, but haven't really warmed up to it. I previously found the same thing with my 17-40mmL.
I use it on my 5D MK III.
I do low light photography, and have analyzed the photos I've taken. Almost all of them are at f/2.8 and fall in the 24-35mm range of focal lengths. They also required that I boost my camera ISO to very high levels, often 25600.
I'm thinking of selling it, but I hate to. It is a very sharp lens, no problem there, I just find that I have little need of super wide angles.
Perhaps a 24mm L to go with my 35mmL, or a 24-70mm f/2.8 to replace it?
Here is a example taken at 35mm, ISO 25600. It was in blue light, which explains the tint. There is lots of noise, but it prints well at 8 X 10.
16-35mmL @ 35mm ISO 25600
I think I like the one taken with my 85mm f/1.8 at f/2 and ISO 16000 better. Maybe a 85mm f/1.2?