Summary: Great lens with a moderate zoom range. If you're shooting low light, purchase a f/2.8 or lower aperture. The STM is completely silent, and has little hunting for focus when at the right distance and light. Purchase if you are in need of a good video lens.
Excerpt: I used this lens in an ocean environment, as my one and only lens. Can't say enough good things about this lens. Great quality optics. Covered the range necessary to get great shots quick and easy. Its a must have lens for all photographers at any level.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Lightweight
Excerpt: I'm a pro photographer using both the Canon 5D MkIII and Canon 7D professionally, and the Rebel T3i for travel/vacations. I recently purchased this lens because I wanted more reach than I could get with my Canon EF 24-105L. As soon as I got this lens, I put it to a very simple test: how well would it render a small, tabletop subject shot hand-held? I think the attached image speaks for itself.
Pros: Fast / accurate auto-focus, Lightweight, Nice Bokeh, Strong Construction