Its main feature is that the coffee is entirely prepared in glass; there's no contact with metal components. Because it operates by a vacuum principle, coffee is always infused at the precisely correct temperature every time, and over-extraction is not possible. It's the brewing method for romantics, and is prepared at the table with heat provided by the spirit lamp. In fact, some fans of the vacuum pot say that it yields coffee that tastes just like it smells. But a vacuum coffeemaker, which resembles laboratory glassware, is cumbersome and fragile, and requires painstaking attention and careful storage.