The Flavour Map was created by Dave Broom, whisky writer, and Jim Beveridge, Diageo master blender. The intention was to provide a structure to better understand whiskies and how to group them in terms of their flavours. Unfortunately, regional definitions (Speyside, Highlands, etc.) are not a guarantee of flavour. The Flavour Map's vertical axis starts at the "Delicate" end with whiskies that are clean and pure. The more complex the whisky, the higher up on the line it sits. As soon as any smoke is discernible, then the whisky moves across the central line. The smokier it is, the higher up on the line it is positioned.
The horizontal position moves from "Light" to "Rich", starting with the lightest and most fragrant flavours; as you head towards the centre, you move through grassiness, malt, soft fruit and honey. As soon as you cross the central line heading towards "Rich", the influence of the cask becomes more important: American Oak's vanilla and spice to being with, before the dried fruit of of ex-sherry casks become the dominant character towards the right-hand side.
It is important to note that the map is not saying any whisky is better than another. It acts as a simple guideline as to what the dominant flavour characteristic is, and gives an idea of similarities, and differences, between whiskies.