Pros: Lightweight and nice focal range
Cons: Price, soft pictures, and dark corners
Bought the Canon 20D and 17-85mm (kit), tried it for 3 weeks, then decided I wanted the 24-70L. Sold it for a loss because it was after 7 days that NY camera stores allow on the return policy, remember this when buying. I took pictures with a Sony V1 and compared them to pictures with this lens, and the Sony pictures were sharper. Also, in low light when using the flash, the corners of the pictures will be dark.
Don't buy this as a kit, because if you decide you don't like the lens, you'll have to send back your camera, even if it's working fine. Buy the camera body, and lens separately, and go with something else. There are many better lenses out there for the money. After you use this lens for a few weeks, you'll be wondering about the "L" glass. If anything, start with the 17-40L if you can't afford the 24-70L and grow into better lenses.