A 15 year old single malt Scotch from Glenfiddich Distillery, made up of whiskies matured in American bourbon, sherry, and virgin oak. Inspired by the classic sherry-making bodegas of Spain and Portugal, the 15-year-old whiskies are left to mellow and intensify in a solera vat, a large oak vat that hasn't been emptied since 1998.
Sherry, citrus - orange in particular, dry wood. Slight suggestion of smoke?
Medium, Sherry, raisins. Fruitcake, spices, sweetness.
Candied fruits, raisins, spices, Christmas pudding, oak takes over.

Unrefined, tastes & feels like a young whisky with no distinct character. Generally disappointing.
Possibly my favourite speyside, nicer than the 18 and distinctly richer than the 12. Very smooth. Always laugh at Americans reviewing Whisky - see review "nothing burger, overpriced" below. Compared to what you pay for the garbage produced by their country their criticisms are laughable.
Love it. Of the Glenfiddich offerings the Solera Reserve is by far my favourite.
Very friendly, smooth and approachable for beginners. You can't go wrong with this, unless you're trying for something complex. It's not bland, it just isn't super interesting. If complex and interesting is what you're looking for, try a few drops of water in it and see it open up. It'll be a little sweeter and a lot more interesting.
Innocuous, no kick, no character--nothing, literally, to write home, or a friend, relative or even a whiskey review website about. Fairly smooth, yet utterly unmemorable. Bought for $75, worth maybe $25. HUGE ripoff.