Summary: I love this lens. Given the price and the inclusion of stabilization, this thing beat Canon's 24-70mm f/2.8 all day. Of course L-glass is going to be top notch, but Canon dropped the ball on stabilization. And for what you can get out of this lens, there's just no reason to pay Canon's premium. If you pixel peep and agonize over every single dot, there's really no helping you.
Excerpt: I use this lens for everything from weddings to catalogue photography, and it stands up to the Canon 24-70 L on sharpness and overall quality. As an added bonus, this lens has image stabilization, which the Canon does not! So far in my use I've been super impressed, and am really pleased with this purchase.
Pros: Consistent Output, Durable, Fast / accurate auto-focus, Nice Bokeh, Strong Construction
Excerpt: I've used this lens for six months so have a good idea of it's performance. After hearing all the hype I was hoping for better sharpness than my 24-105, but found it not as good as the Canon at any aperture or focal length. The problem seems to be the AF, which is unreliable. If you focus manually the lens is as good as Canon, though not better (however, I seem to have a blueprint-perfect 24-105 copy, FWIW).
Excerpt: Well, after reading a lot of reviews on this lens sometimes very polarized I still decided to go for it. Absolutely do not regret buying this lens ! This lens is way better than my kit 24-105 F4.Auto focus works very well on my Canon 6d even at f2.8. Lens is very sharp thought out the aperture range. My only remark is about vignetting in the corners when it is at 2.8. But this is easily correctable.
Excerpt: My lens also has auto focus issues but it works ok. I feel that the images are soft. Does not compare with the Canon 24-70mm f/2.8 either version. I paid $ but as I write this I see a price of $ which I would never pay for this lens. The lens has no lens creep. Image stabilization woorks very well.
Excerpt: I bought this lens for portraits, landscapes and distances too short for my Canon 70-200. I have taken a lot of portrait shots and candid party shots with and without the 580ex flash. It works well on both my EOS 50D and 70D. I am very pleased especially with it's no flash low light performance. It's not a cheap lens unless compared with the Canon 24-70.
Pros: Consistent Output, Easily Interchangeable, Fast / accurate auto-focus