Years in oak change the colour, the taste and the price.
What the wood does
Vanillin from oak gives vanilla and coconut. Tannins give structure. The sharp edges of the alcohol wear away.
Which casks
New oak gives plenty of wood. Used sherry or bourbon casks give fruit and sweetness.
The age on the label
Unlike whisky, there is no legal minimum age for calling a jenever aged. Look at the year, not at the word.
How to drink it
Like whisky: room temperature, small glass, no ice.