The thin blown glass keeps the stout cooler for longer and retains head better than a thicker glass. It contains the aromas of the stout rather than letting them slip away. The glass narrows up to the rim, focusing the aromas to the top of the glass to enhance the drinking experience. The more aroma, the more flavor.
The conical shape of the bottom of the glass lets sediment settle and pushes aromas upwards to the bowl-shaped body. The glass holds over 21oz, more than a standard pour, allowing for plenty of head space.
Nucleation on the bottom of the glass allows for bubbles to form. These bubbles rise to the top of the beer and when they burst release rich aromas, improving the experience of the beer drinker.