Jason wrote about that on MALT-review:
"Glenfiddich Spirit of Speyside 2017 Review
Colour: cinder toffee
On the nose: there’s a melting pot of the wood tannins mixing with a drying ashy peat. A rich decadent honey combines with chopped walnuts, ginger and a hint of campfire smoke. This gives the vanilla a dirtiness I adore and added depth with dried cranberries, fig rolls, warm caramel, pork scratchings and almonds.
In the mouth: it’s a fruity peat that comes through initially and underpins the whole experience leaving a smoky finish with a hint of salt. In-between there’s a hill climb (in a Ford Fiesta XR2 Mark 1) of flavours with caramel, brown sugar, all-spice, toffee apples, crackling and peanuts.
Conclusions: Much like the previous Spirit of Speyside 2015 bottling from Glenfiddich, the combination of the new make spirit and sherry cask have married rather than clashed, producing something harmonious and devoid of the aggressive wood that sometimes a 1st fill sherry cask can create. The peat really comes through on the palate and takes the experience in a whole new direction. I’m a BMW Series 3 kind of fella and this dram has the foreboding presence of such a vehicle appearing suddenly behind you on a sweeping Speyside road, only to vanish from sight. It’s one of my favourite Glenfiddich’s and a triumph; no not the car manufacturer. Score: 9/10"