Judy: I rented this lens for a two-week trip to Costa Rica where I shot a lot of different types of wildlife, including birds. It performed flawlessly on my Canon 7D and I was able to handhold it for the majority of my shots (and I'm small and not especially strong), including on a boat ride. I used the IS Mode 3 (which is new on this lens), and was amazed at how slow a shutter speed I was able to use and still get a tack-sharp image. Its focal length is a bit short at times for birds but the lens provided great results with my 1.4x II extender. I was less satisfied with images taken with the new 2x III extender (which I also rented) but for many people the image quality might be acceptable (sharpness is paramount to me). It also works well for portraits with its amazing bokeh. If you can afford the steep rental cost, rent it! I can't recommend the lens enough, and it's my dream to buy one some day. I estimate that I wouldn't have gotten 90% of the shots I did had I taken a different lens (e.g., 300mm f/4 L IS or 400mm f/5.6 L). I rented the 300mm f/4 L IS for a trip to Trinidad in 2010, and though it's a very sharp lens with good bokeh and is much lighter, it simply can't compete with the 300 f/2.8 L II. If you're going to spend a lot of money traveling, take the best glass you can afford -- you'll never regret it.