I had the good fortune to buy some high grade Mimmo briar with about 10 years on it (most of it was purchased in 08 and sat, I bought it in 2018). Compared to fresh wood, it was much harder, and a uniform golden brown all the way through, where new it is white with a sort of pinky/copper hue to it. Cutting it, the smell is sweet and a little yeasty, Rainer Barbi spoke of good briar smelling like baking bread and this is not far off. I don't know what's happening to briar as it sits, it sort of petrifies/oxydizes. If you look at most pipes where you can see the briar raw, in an uncoated chamber, you'll see very white briar. Radice, Don Carlos, etc. You look in a Castello, it's brown, always, never white. Truly ready.
It's not about price or mystique for me, I'm not here to brag about my Castello collection. I have a few now. Sea Rocks mostly, the cheapest. I've bought lots of 300 dollar pipes and found them adequate or not on their own merits. The last really expensive pipe I bought I hate, I hate how it tastes, it's a real disappointment for me. Not a Castello. I will say my last Castello is drilled a touch high in the bowl, I'm a little disappointed, but the pipe smokes dry and tastes fantastic, so ... okay.
No one is saying no other pipes are ever good (hell as a pipe maker myself I'm not doing my brand any favors coming here and shilling for Castello). No one is saying only Castello are magic. Most of 'em seem to smoke great, for those of us who think that's a thing. That's a real accomplishment in the pipe making world, being known not so much for radical shaping or some patented finish, or making bits 15% thinner than anyone else. Just being the tool of choice for a lot of guys who care.... that's a big deal. It's very, very difficult to set your brand apart as a pipe maker. To do so "only" by making really reliable pipes is almost brave.