I think this is the first pro quality zoom for Micro Four Thirds. This Panasonic lens has the same zoom range and max F-stop as the lenses which are popular, but expensive flag-ship models for full frame cameras, 12-35mm F:2.8, equivalent to 24-70mm F:2.8 in full frame. It's not quite as expensive as the Nikon or Canon equivalents, but it's not exactly cheap either, apparently 1200 Euros. But that's what one might expect for a weather-sealed top-flight lens.
Below is the rather handsome lens on the right, compared in size to an equivalent full frame lens.
My own reservation is that the zoom range simply is too short to really matter much. But longer zoom ranges makes for more compromises in quality or weight/size or price. But it depends on use. Unless it's for architectural photography or for critical large prints, I'm very happy with my Panasonic 14-140mm lens, it has not presented any glaring flaws in my use (unlike others I have tried which always had soft corners somewhere in the range), and that is one heck of a useful zoom range. (This lens has also tested better than the Canon and Nikon equivalents.)