Pros Pros: Outstanding optical Quality. replaced my old, bulky and heavy 100-400. Using with 1.4 extender and some cropping to get similar results!
Cons Mechanically anything but Pro-quality. Banged it slightly against a ship railing and a retaining ring inside broke, rendering the lens totally useless. The solid lens barrel did not show any sign of damage. Excellent outside, lousy inside.
Summary Be careful when carrying this lens around. It may also be a good idea to have the camera turned off when not in use.
Also remember: repairs are expensive and if you do have to send it in it will take some time.
Pros Looks like the F2.8 IS model
Cons Not wide enough, Not long enough, Not F2.8 Mot IS Nevermind !
Summary Worthless for anything you can not stage and get the proper distance from = Not wide enough, Not long enough, Not F2.8 Not IS Nevermind !
Pros Fast, silent zoom with incredible overall picture quality, pleasing bokeh, razor sharp pictures; constant F/4 aperture; light weight; good image stabilization; good zoom range for portraits and outdoor photography.
Cons Price; F/4 may not be bright enough in some situations such as action photography or low light, indoor photography; no tripod collar for the price.
Summary I recently got this lens off of craigslist for a relative bargain but it was still very expensive and stretching my lens budget. I've been shooting with it on my XSi, both outdoors and indoors. For indoor shooting, the camera's ISO settings need to be punched up a bit to 400 or 800 (or less preferably, to 1600 in some cases). Has Canon's USM focusing feature and boy does it work! I was able to take a shot of my light sleeping infant daughter without waking her up and my hyperactive dog as he played with a toy. I think it's best suited for outside portrait and outdoor landscape shots, although the indoor shots came out very nice as well. The background blur is amazing and people (or any subject) pop out. Pictures look razor-sharp across the board from wide open on down. There is some barrel distortion and pincushion distortion but not more so than any other zoom. I didn't notice any vignetting at any aperture. Purple fringing seems to be non-existent; details look beautiful and colors look very nicely rendered in the camera's jpeg large fine setting. The IS feature also works as advertised. I was able to get good, decently sharp pictures hand-holding at 200mm down to 1/15 in good, outdoor light, ISO 200 and 1/60 indoors, fairly low light, ISO 800. It does include a lens pouch and a hood, however, for the $1200 or so Canon asks retail for this lens, I thought a tripod collar would have been included. That minor grip aside, if a person needs a good, medium telephoto zoo lens and can spare the cash or find a good deal, this is the lens to get.Need to add that the L-lens is built like a tank! The lens lens slipped out of my bag, recently and fell on to concret for about a 1 meter drop. As my heart dropped and after nearly soiling myself, I checked the lens and the filter that was on it couldn't be salvaged but not one scratch on the lens. Amazing!
Updated on Mar 12, 2012
Pros Relatively light weight. Fast focus. Internal zoom so front doesn't rotate making polarizing filters easy to use. Sharp images at all zoom settings. Image stabilization works as advertised.
Cons Not as telephoto as one might think. No tripod mount ring. Manual focus ring too narrow.
Summary I purchased this lens shortly after acquiring my Canon 40D in December 2007. I have been very satisfied with the lens in most every manner. It's not too heavy to work with for hours at a time. The auto-focus is both quick and accurate. The image quality is sharp across the zoom range and the issue of barrel and pincushion distortions only come into play if you are shooting anything with lots of horizontal and/or vertical lines. If you're shooting nature stuff there is no need for concern.
I purchased it for shooting wildlife, but have found that its 70-200mm range (even with the 1.6x conversion factor with my camera) limits it somewhat if you are trying to shoot anything small (think birds, chipmunks, etc.) at ranges beyond 40-50 feet. Well, if you are trying to get great closeups, it becomes an issue.
It is a good lens for shooting events with lots of people - great for getting nice close-ups of folks without having to actually get in their face.
Pros Image quality is superb. Also: fast focusing, rugged, good image stabilization, weatherproof.
Cons Worst is cost--try rationalizing it as $110/year for a decade. Everybody wants a wider aperture. It's bulky if you'll always just use cameras with APS-C sensors. $115 tripod lens collar is overpriced. Not telephoto enough for shots of distant birds.
Summary Expensive, but it has great image quality, build quality, durability, image stabilization, weatherproofing. I've used this lens for more than two years, including many backpacking trips, and I love it. It's also good for photojournalism, even without f2.8 aperture, if you can shoot at high ISO. It's rugged, seemingly immune to very dusty conditions, and modestly hefty. The f4 aperture could be wider, but for me it's worth it to have the cost and weight savings over Canon's f2.8 model with the same 70-200mm zoom range. Included lens hood is nice. The IS is good enough to let me take many photos at 1/10 sec even all the way at 200mm (no, not all come out, but enough do). Would be five stars out of five if the price were a bit lower.