The entire brand, Caswell-Massey, is a curiosity. On the one hand, it is one of the oldest perfume houses in the world (founded in 1752), and on the other hand, it is an American brand, not a French or English traditional house.
On one hand, they offer incredible classics (various legends surround the fragrances of the house, such as that these were the favorite scents of American presidents, including not only those from recent decades like Eisenhower and Kennedy but actually also George Washington himself), while on the other hand, they have - quite American (?) - no qualms about changing the original formulas as needed from time to time. Thus, it remains uncertain whether the colognes that can be purchased today are still identical to the old formulas, resemble them, or have been completely transformed.
Especially with Greenbriar, I have a slight suspicion that the old version must have smelled quite different. I still possess a sample that is about 10 years old, and I must admit that it has a distinctly different effect than the current version of the fragrance. Be that as it may... I will now orient myself to the current formula, as it has captivated me.
Without many words, the scent can be very well described if one simply thinks of Cool Water. Now, that wouldn't be particularly original, as there are many Cool Water clones by now (from Creed, Bond, Floris, Truefitt & Hill, etc.), and no one really needs an additional twin. The (still good and affordable) blue wonder water is usually sufficient.
In fact, Greenbriar is a highly pleasant new and reformulation in the Cool Water direction: it is less cool, rather herbally soft, as if one were lying on a mossy meadow and also perceiving the scent of various fresh herbs. At the same time, Greenbriar is warmer, a bit softer, and rounder.
Anyone who would like to try the scent is dependent on a blind purchase, for which I cannot take any responsibility. It is currently only available from American eBay sellers who offer the scent through the German eBay site, but in my experience, they deliver reliably. However, the shipping duration is annoying. With customs control, it can take a few weeks. At least: Greenbriar is among the affordable colognes. Even the shipping costs hardly add any unpleasant surprises.
My rating above explicitly reflects my preference for Cool Water variants. Those who find little appeal in these scents should stay away and deduct about 20 to 30%.
For fans of curiosities, classic brands, and enthusiasts who are not averse to Cool Water, it is certainly worth a try.
If "Cool Water" weren't used so excessively, its reputation here would certainly be better. I can definitely imagine a mossy-herbaceous version being quite exciting.