As the English wikipedia states:
The paper is considered to be high brow. Its political direction is centrist to social liberal, but has oscillated a number of times between slightly left-leaning and slightly right-leaning. It is known for its very large physical size and its long and detailed articles.
In case you wonder: I’ve read the thing regularly since 1989. “High-brow” (as in German “Bildungsbürgerlich”) and “long and detailed articles” is a very good way of characterising its style. Provided you can read German it is a fascinating window to a part of German politics and society which doesn’t always make it to international media. On the other hand, Die Zeit is also very much opinion-based and its interpretations of German and European politics should be read critically.
Oh, and don’t forget to check out the paper’s recent and very serious take on the subject of German humour.
Hat tip: Internetbrus.