The best zoom lens I’ve ever used. My second favorite lens of all time next to the 50mm f/1.4. If you are shooting film or a full-sized sensor, the 24mm is perfect for shooting in tight spaces (parties, weddings) and on the other end 70mm is a pretty nice zoom if you see some action across the room. The f/2.8 aperture throughout is the best attribute, and the reason why this lens is so expensive. It takes a significant amount of glass to shoot at f/2.8 at 70mm. The focus ring is fairly large and easy to adjust. Autofocus works pretty well, although at 24mm it is best to use hyperfocal focusing. Besides the performance, this lens looks awesome. It is a beautiful addition to a larger body Canon SLR. The lens hood is rad as well.
Although it is such a great lens, I wouldn’t use it all the time. I would buy this lens third, after a 50mm and a fisheye. Then it would be a tough decision between this and a 70-200mm f/2.8, since they are in the same price range. This lens is perfect when you are moving around while shooting, or for basic travel photography. It is by no means a replacement for a 50mm.
This lens will cost you ($1,280 new), but it is worth every penny. A decent alternative would be the Canon EF 24-85mm f/3.5-4.5. It’s not as fast or sharp, but much less expensive ($379 new) and will get the job done.