American cheesecake is dense - brick-like. You could probably hurt someone by hitting them with a New York style cheesecake. It's also rich; I don't even want to know how many calories are in a slice of American cheesecake.
German cheesecake is light and fluffy. It's got a crust that's to die for and a creamy melt-on your tongue filling. It's great stuff - and almost low cal. (OK, that last one may be an exaggeration, but it's good stuff, if I may say so myself.)
Unfortunately, as many German cheesecake lovers discover when they get to the States, one of the necessary ingredients is not available for purchase in many parts of the United States. Making cheesecake requires "quark" - a white cheese that has the consistency of sour cream, but the flavor of a cottage cheese or ricotta. Here in Kentucky, I can purchase quark in Cincinnati at Jungle Jim's for about $7 per 1/2 lb or so. If I ignore the cost of the road trip to Cincinnati, that amounts to a $30 cheesecake, and that's just a bit much for an everyday cheesecake.