I've had this lens for over 8 years now and I'm still using it. What I really like about it is that it is a true zoom... you can focus on a subject at 70mm and when you zoom out to 35mm, the subject is still in sharp focus. Most zoom requires you to re-focus.
One known problem with this lens though is that because it is a push-pull zoom, there is the zoom creep issue. When you zoom out to 35mm and tilt you camera/lens up, the barrel will slowly creep back down to the 70mm position. This is only a major problem if you are taking picture on an inclined plane... but for this to really to be an issue, you'd be having your system mounted on a tripod. Otherwise, you left hand would normally be holding on to the lens!