One of my mentors, an incredible photographer at the very top of his niche in the world who was tragically killed on a shoot, Marc Paris, used the 12-24 almost exclusively. He had the money to buy pretty much any lens and camera made but he swore by that 12-24 on his 5D MkII.
If you look in any high end motor yacht magazine from two to ten years ago, chances are there is a Marc Paris photo shoot in there, often times more than one. Every interior shot was done with that Sigma 12-24. And if you like the lighting on those interior shots know that he did it all with three flashlights (torches) and a mixture of ambient and light painting.
A true master of light and sorely missed.