This is a really nice compact lightweight and sharp lens that perfectly complements M series camera. In fact you might expect it to be a lens for the more compact M43 system.
The lens is sharp throughout the whole zoom range. It can be used with confidence at full aperture if required. Peak performance is achieved at about one stop down from maximum. Stopping down to F11 sees a slight drop in sharpenness due to diffraction. F16 is a bit soft for similar reasons and I would not recommend using F16.
The Zoom action is very smooth through the range. The focus by wire is also very smooth but needs to be adjusted slowly so that the motor can keep up with focus input. The manual focus is much smoother than the usual manual focus found on consumer AF lenses.
AF is virtually silent due to the STM technology.
The lens mount and body are all plastic but the lens feels tightly built. There is no wobble at full zoom extension.
So this is a very good lens with only one problem..... it is very slow. The max aperture is 3.5 to 6.3. The value quickly reduces to F6.3 at about 70mm. The slow apertures should not however be a problem for general photography. The built in IS is effective if the light is low and slower shutter speeds are required.I have taken a shot at 1/4 sec at 18mm with no camera shake.
