It's a beautiful finish. Looks like a Berluti. Lots of hand applied finishing probably done with a combination of dyes and colored waxes embedded with a buffing tool. If my somewhat limited understanding of the methods are accurate.
Will it be as durable as a 'regular' calf leather - certainly not - will it come undone in just a few wearings - certainly not. But the finish can be reworked/reapplied. (Burluti has people on staff in their stores who can refinish the shoes in just a few days)
Given Burluti's success with these sorts of highly patinated shoes they are becoming more widely offered in France and a few folks have set up shop as professionals who will rework your existing shoes into a similar finish for a few hundred Euros. Although I doubt that these repatinators can claim to exceed G&G's quality.
I'm sure the purchaser is well aware that he is not getting a 'work horse' shoe here and is more than willing to pay for whatever additional maintenance will be required. As long as his shoes are superior to everyone else's around him.
The shoes fu**ing rock!