I've worn the Peau d'Espagne now for a couple of days from a sample and simply, I'm blown away.
I find it hard to describe how I feel about it. It's old yet has a modern abstract feeling about it. Very much un-mainstream. I absolutely love the birch tar note in there and that adds a real "old world" woody aspect to the fragrance. The whole time this is going on you have faint floral/herbaceous notes floating about in there and they are sitting at the side on a pillow of talc.
The star of this scent though is the medicinal/balmy/ambery binding in the base which along with the dryness of this scent, brings all the notes together. "Leather " fragrances can be cloying (GFT Spanish Leather) and can sometimes be over the top (Knize Ten). I agree with one of the previous reviews saying this is stronger than the above but it is much more perfectly balanced than any other leather I've worn before.
I had previously started a thread in the forum here about finding a scent which was the smell of walking into the entrance hall of Santa Maria Novella in Florence. A lot of answers came back but this is that scent (maybe adding in a little of SMN Pot Pourri), this is alchemy, this is Santa Maria Novella.
The smell of a perfumer in a centuries old building with surrounds just as old. Old oak which has soaked up all the fragrances past and holds those scents as memories for everyone to smell in the future.