I bought the 12-100 f/4 just yesterday and it is rapidly becoming my favorite lens. It is clear, sharp, and the 12-100 range (24-200mm in 35mm format) covers most of my shooting requirements. The combined in lens stabilization and in body stabilization in my OM-D E-M5 Mk II is astonishing, allowing hand held shots at 100mm using 1/4 second or even less. I have tried test shots down to 1 second with acceptable results.
The lens is large, larger than I expected, but it is well balanced on the camera (I use a grip and the PBH). It does not creep when carrying the camera and lens on a strap and it really does not feel that heavy compared to the 12-40 f/2.8. It may still be too large for a tourist setting, but will try it anyway.