I bought this lens used, and deliberately over the mkII version for the 77mm filter size.
I already had the 24-70mm f/2.8 and the 70-200mm f/2.8, so I liked the idea of having all of the lens be able to share the same Cokin mount. Combined with the price I paid for a mint condition used copy of this lens and that sealed the deal for me.
I've used this lens a lot, handheld indoors with my kids and for shooting video on the 5D2 and for some awesome perspective shots.
I used to own the 10-22mm Canon on my 40D this lens, while a lot heavier, feels more like it is built like a tank.