Excerpt: I am a wedding and portrait photographer, and have had the first version of the 70-200L 2.8 IS lens for about 10 years. This f/4 IS lens is much lighter, easier to hand hold, has excellent image quality (probably better than the 2.8 v1) and better IS.
Pros: Ease of handling, Fast / accurate auto-focus, Lightweight, Strong Construction
Summary: Because of the cost, I weighed this purchase heavily, but I'm so glad I bought it! My boyfriend and I were going on a trip to Africa, which honestly, wouldn't have been captured so well without this lens.
Excerpt: I am a semi pro photographer that made the switch from another brand 70-200 2.8 lens to the Canon 70-200 4.0 lens. I am in love , the new one is half the weight and size, clarity unbelievable, ease of use; put on camera and go.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Lightweight, Nice Bokeh
Conclusion: This lens is so good it is almost unbelievable. The color this lens captures is beautiful and is very impressive. The lens zooms in and out with ease and focusing is precise and easy to work in manual setting.
Excerpt: After tons of research and back and forth between f/2.8 vs f/4, I purchased the Canon 70-200f/4L IS USM. This lens has incredible everything as described. At half the weight of the f/2.8, smaller size, and hundreds of dollars more in my pocket to buy another L series lens you can't go wrong.
Pros: Consistent Output, Easily Interchangeable, Fast / accurate auto-focus, Nice Bokeh, Rugged, Strong Construction
Excerpt: I had been debating between this lens and the 70-200mm f/2.8L non-IS. I'm very glad I went with the f/4L IS because of the smaller size and the IS. There is a clear difference in sharpness when I have the IS turned on in lower light conditions.