I bought the 12-24/f4 (DX) secondhand almost three years ago, and have been very pleased with it. Read a lot of comparison, and user, reviews in the Brit mag Amateur Photography at the time, and it seemed to perform better than most it was compared to.
I'm totally happy with its performance and the build-quality feels great in the hand and on the body.
I have a few pix on my Flicker stream that were taken using the 12-24 lens - "Small room", "Peugeot 404" and "Citroen Light 15" are taken with it, as is the shaky handheld (1/15th sec) of the "Tour Down Under 2012, stage 6".
May be of interest.