Since the majority of all followers of religious belief in Germany are Christian, Christmas is a pretty big deal. In most of the households I know, however, it is a relatively secular holiday and predominantly an incentive for everyone to travel home and spend time with their families. As in other European countries, most people celebrate on the evening of the 24th, and spend the following two days with their extended families, consuming massive amounts of food. A traditional Christmas feast incorporates roast goose and is followed by lots of candy.
One of the beautiful things about Christmas is the traditional Weihnachtsmarkt (Christmas fair) which most cities will host on their market square. Shops are closed on the 25th and 26th, but the indescribable amount of hasty shopping before the 24th might compensate for that. Here are some pictures of Glühwein (hot and spicy mulled wined) and Lebkuchen (gingerbread), two of the most quintessentially “Christmassy” things I can think of. The Weihnachtsmarkt pictures are from Ludwigsburg, the town I grew up, and Tübingen, where I studied.