I'd always heard about this but it eluded me. Finally had a chance in a blind tasting against Elmer T. Lee and a Blanton's. This came across as dusty. Very dry aromatics.
However, I revisited it later based on recommendations. It opened up a bit. Things evolved. There were cedar notes with vanilla and caramel and noticeable cherry.
Notes on the palate had oak with hints of vanilla that evolved into a warm syrup texture. There was an orchard fruit associated to this.
Oxygen causes a lot of reactions to happen within the barrel. In fact, oxygen applies tenfold the number of reactions. This process doesn't stop when out of the barrel. Allowing oxygen to react to and to allow natural evaporation of lesser particles the bourbon can change. In this case, amazingly better.
Green apple jolly rancher.