This is really nice. I love imperial stouts, but never really loved whiskey barrel aged beers (don't really like whiskey) unless the aging in those barrels is more of a complement to the beer rather than a dominating flavor. This is a mix of barrel aging and that aging really adds to the complexity here.
One other beer I had that was this memorable was a barrel-aged Alesmith Decadence at Alesmith brewery. That was just in whiskey barrels, but done so for a shorter time where it really was a subtle complimente to the original beer.