My impression is somewhat mixed, but the bottom line is a viable alternative.
The Verarbeiotung is really top, solid metal and nothing wobbles, but a richtgiges heavyweight with tremendous size. It's been closed about 7cm long, 14cm even at full telephoto. Camera One must therefore always hold with 2 hands on the lens because of the weight and trigger one must also still.
The autofocus is a little slower than with 10-30mm and 30-110mm lenses, probably due to the larger masses. Although the light intensity is specified slightly less you always need indoors despite VR just in individuals a flash, otherwise you get out blur-no shots. The 30-110mm works much better here, even with almost mamximalem Tele. This also makes the 40-50mm a nice bokeh. For people photography, family festivals and events I will still have between 18.5mm and 30-110mm change in the future.
The strengths are to fnd in landscape photography outdoors, so for holidays and excursions, if you already have a backpack with to carry the weight. The pictures are really nice, sharp and well-lit outdoor. Last year in Battery Park, I would have liked.
Conclusion: good all-rounder when you're on photo tour in cities or in the nature, weight and size but then in the DSLR League.
Always there too large and heavy, not very suitable for people photography.