The French version of Dpreview is Focus Numerique. And they just tested the new Leica 8-18mm lens. Here is the google translated text:
Impossible not to recommend this ultra wide-angle zoom that combines qualities in all points of view.
The weight is very contained, the grip is excellent, as are the adjusting rings. We would have liked a third to manually adjust the diaphragm. The quality of construction is perfect and the design, very successful.
Finally, on the optical quality side, it is very good. The lens delivers rich images in fine detail at all focal lengths, from the largest openings. In addition, the objective has a beautiful homogeneous behavior. It suffers however from a lack of homogeneity between the center, two thirds and the extreme edges of the images.