Picked up a 20-35L on ebay a few weeks ago in MINT condition for just $600 shipped from Japan (btw, I've always had way better luck buying from Japanese sellers than anywhere else, they are an honest bunch, and their packaging is unbeatable).
It doesn't have as wide a reach as any version of the 16-35, but I generally don't like going that wide, and find it more convenient to just zoom back to my preferred 20mm. Same goes for the 17-40, I find the 40mm end just awkward. I also love the all-metal build and the solid heftiness of the 20-35L.
Anyway, took it out for a spin at a day at the stadium the other day, and thought I'd share! All photos taken with the 20-35L and 6D, processed in Photoshop. A few photos are straight out of camera, like the flowers shot. I always add extra vignetting to my photos, even though the 20-35 has moderate vignetting already. It's a tack sharp lens wide open, and handles great. 
I'm sure the lens has a few flaws that would be dealbreakers for some, like the vignetting, or distortions, but I am no pixel peeper, and find it great in real world use.
EDIT - I would definitely not use this lens on crop though, because it makes it a silly 35-50 equivalent, and there are far better APS-C options
http://www.thingsbyjohn.com/Levi-Stadium/
