Excerpt: I think the photos speak better than I can. The moon was shot on a tripod. I used a remote shutter switch and a 2x lens extender, which meant I had to manually focus. I shot that photo with a 600mm zoom setting, at f/16, 1/100 shutter, ISO-200.
Pros: It is EF, not EF-S. Has USM.
Cons: No IS, Image Stabilization. May feel heavy to some.
Excerpt: Within 24 hours of using this lense has been the best thing ever! My backyard is filled with ton of birds including Orioles and it was difficult with my standard lense because they were so far away but now with the new lense I can get up close photos.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Nice Bokeh, Rugged, Strong Construction