I really really wanted this lens to work for me...
6 March 2014
Summary: I really really wanted this lens to work for me because its affordable but unfortunately it didn't. Don't get me wrong, I love the constant 2.8 but it can only focus in bright sunlight. Indoors, in relatively 'normal' lighting, it just can't focus. It keeps hunting and cannot lock focus so you have to manually focus. I used it mostly for video and if you're always manually focusing, its a keeper.
Excerpt: I was lucky to pick up a used version of this lens for $280 for use with my Canon 5D Mark III (as a general walk around lens).I just couldn't see myself spending $[$] for the Canon EF 24-70mm f/2.8L II nor did I have the money for it.I agree with the other comments here on sharpness. A little soft at 28 + 75mm at f/2.8. But you only need to go as far as f/3.2 - 3.5 and the softness disappears.