It might be a bit kitschy: to imitate the aged and appearance of a weathered stone wall (with pieces of different stones representing fill-ins, repairments and strata of change over time). Especially if it is used as a skin for a historic museum - like in Ningbo (China) in this project by Wang Shu (Amateur architecture studio).
But still, the look it brings is really nice. It could've ended up looking like a historical version of Disneyland - completely fake - but this building actually looks like it's been there forever, fitting into the surroundings. At the same time it stands out in the surrounding environment, and looks very contemporary.
And the material also really fits with the architecture of the museum: it looks solid, monolithic and heavy. This materialization of the facade gives it more tactility and texture in it's massiveness - giving the building a bit if a Chinese Zumthor-like feel. Too bad the interior seems a bit less poignant, in comparison (in as far one can judge from a couple of photos on the internet, that is)...
The images come from archdaily.com, by the way.