It fills a huge hole in the focal length range between 120mm and 250mm. One could argue that the f/5.6 is disappointing but at f/4 it would be very large. For me, who will use it exclusively as a landscape photography lens to do exactly what I said above, fill the gap, f/5.6 is not an issue. Certainly for studio photographers, the lens' purpose could be questioned but for those of us that hike many miles with their gear, a three lens system with the 23, 32-64, and 100-200 is dramatically more size and weight manageable than the current state of carrying the 23, 32-64, 110 or 120, and 250. It saves around 5 lb or so!