The Noctilux no doubt is an impressive lens, not just because of its size and weight. Center resolution is very good to excellent throughout the tested aperture range. In contrast, though, the image borders and corners are very soft at large apertures, but improve considerably by stopping down.
In terms of build quality, the lens certainly meets even the highest expectations.
Typical for such a fast lens, vignetting is very pronounced wide open and slightly stopped down. Surprisingly, this is still the case when the lens is 6-bit coded and thus the camera applies some correction.
Bokeh is generally very smooth, except for the image corners wide open, but depending on the subject this may not be an issue at all in the field.
Given the extreme challenges the lens design must have given the Leica engineers, this is no doubt impressive performance.
But, is all that worth the enormous price? Well, it depends. First of all, the Noctilux ASPH certainly is one of those lenses one needs to learn to master. In addition, the differences in rendering compared to other fast, but far more affordable lenses are often subtle, but of course these lenses do not offer the speed, that "magic" aperture number below 1.
To those who either simply need the speed or really care about the rendering characteristic, the Noctilux may well be worth its price. One should be aware, though, that the most expensive Leica lens is not necessarily the best one, but no doubt one of the most special ones.