Definitely a GREAT lens. I use it for 75% of my shots. It is heavy, though, so I do like to switch over to a prime lens if I need to throw the camera in my purse for an outing with my daughter. The wide aperture is wonderful for low light too!
Check out the 50mm f1.4. It's a third of the price, and the focus is SUPER sharp. You have to get used to not having a zoom, but I think the images of that focal length are some of the best I've ever taken.
Hope this helps!