Does the whiskey glass actually matter?

It would be more consistent with the rest of this site if the answer here were no. It is not, and pretending otherwise to keep a contrarian tone would be its own kind of dishonesty. But the scope of the effect is narrower than a glassware brand will tell you, and the boundaries are the useful part.

Whiskey drunk neat, at room temperature, being paid attention to. In that situation the shape of the glass changes the concentration of aroma arriving at your nose, and since aroma carries most of what you perceive as flavor, it changes the experience of the drink in a way anyone can verify at home with two glasses and one bottle.

This is not a subtle marketing effect. Pour the same whiskey into a tapered nosing glass and a wide tumbler, and the difference in what you smell is immediate. It is the reason distilleries use tapered glasses for tasting and the reason the Glencairn is on almost every serious whiskey shelf.

The moment ice goes in

Cold suppresses volatility. A chilled whiskey is releasing far fewer aromatic compounds than a room-temperature one, which means there is much less for the glass shape to concentrate. For whiskey on the rocks the glass's job becomes practical - hold a large cube, sit stably, drink comfortably - and that is a rocks glass, not a nosing glass.

In a cocktail

An old fashioned is a constructed drink with sugar, bitters and dilution in it. The glass is a container. Buy on capacity and weight.

For whether the whiskey is any good

No glass improves a bad whiskey. A tapered glass concentrates whatever is there, which for a harsh spirit means concentrating the harshness - one of the few cases where the right glass makes the drink worse.

Very little, to get the effect. A single Glencairn-style nosing glass costs less than a bad restaurant pour and delivers essentially all of the shape benefit. Everything above that price is buying material, weight at the base, thinness at the rim and looks - real things, none of which are the aroma effect.

Which makes glassware unusual in this category: the cheap version works. That is the opposite of the situation with decanters, where the money buys craft, and with whiskey stones, where no amount of money buys the advertised effect.

For which shape does what, see whiskey glass types. For choosing one as a present, how to choose a whiskey glass.