It is a beer that has a very heavy head on it when poured. It is traditionally served in the long tall and shapely glass (usually 20oz size).
It has has extreme aftertaste that I find appealing. The taste is very strong. People do associate it with Hefeweizens, and it is usually unfiltered. You have to try it to experience it, because it is unlike ales, stouts, lagers, and hefewiezens.
I would say in Germany from most popular to least the style of beer goes 1)lager (which they call pilz), 2) ales, 3) weissbeers, 4) and then everything else.