The 2010 edition is 12 years old, is 95 proof, and it cost $37. The '09 is 12 years old, is 97 proof, and costs about the same as the '10.
The '10 opens with a complex woody aroma with a bit of ginger, leather, rye, juniper, dark fruits, and light vanilla/caramel..........moderately spicy. The nose is a lot more spicy than the '09 release and less softened by the wood tannins I find so much in evidence in the '09.
A warm, sweet, and rich thickness greets the front of the mouth with the '10. The cinnamony/gingery peppery spice sweeps across the mid-palate on to the back of the mouth, where it dies more quickly than I expected. I find the '10 to be richer, sweeter, with the nose-promised dark fruits, and just a skosh more spicy than the '09........but not as subtle. For those who did not think the '09 suited their palates, they will likely find the '10 more to their taste. It is an excellent bourbon. The dark chocolate of the '09, not present in the '10, is either created by the tannins or abetted by them........I do not know which.
I find the finish on the '10 to be slightly short........and I know of no reason that should be the case, since it has a nice dose of mid-palate spice that I expected to linger longer. The '09 has a longer finish, for what that is worth.
My opinion is that most bourbon lovers will prefer the '10 to the '09 because of its balanced combination of rich sweetness, dark fruit flavors (cherries come to mind), mild drying oak, and zinging spice. It is excellent for those very qualities.
However, for me the '09 is the superior bourbon. The subtlety that comes (my opinion) from the perfect dosage of tannins, even at the cost of some richness, outweighs its tendency toward the sour and bitter (again the dark chocolate). And, the soft sweetness of the '09 is carried to a lengthy and almost delicate finish by those very tannins (again, only my mangy opinion).
Brown Foreman reveals a bit of useful information about the character of these bourbons in the label tags. The '09 tag states that the bourbon barrels were stored in warehouses B (a smaller warehouse) and J (a larger warehouse) on the 5th and 8th floors respectively. These warehouses (according to the tag) exposed the barrels to a great degree of heat during the summer months, which resulted in a rich complex maturation profile.
The '10 tag states that the barrels for this release were stored in warehouse K, on the 5th floor in ricks 42, 43, and 45, surrounded by open space. This environment (according to the tag) allowed the barrels to easily breathe during maturation and develop a rich fruit and spice character.
P.S. For those interested, my opinions were composed before I read the tags, but seem to bear them out. Never once, of course, do the tags mention tannins or dryness in either of these bourbons.
I think comparing the '09 Birthday Bourbon to the '10 Birthday Bourbon shows the importance of location in the storage warehouse, and, to my way of thinking, the effects warehouse location has on what might be called 'accelerated' aging. The '09 Birthday Bourbon tastes more like a 15+ year old bourbon to me........and this is too old for many folks liking.
Do not go gentle into that good night,
Old age should burn and rage at close of day;
Rage, rage against the dying of the light. - Dylan Thomas