It is, because of its Romanesque and early Gothic buildings, considered one of the most significant architectural heritage sites in the Hesse region and ... it is known worldwide.
At least, millions of people have seen it on the silver screen or on their tele in The Name of the Rose (the book was way better by the way). They'd probably not recognise the interior in which the scenes were shot, since these were redecorated afterwards, but the abbey is definitely worth a visit.
Oh yeah, if you like cooking and your German is any good, do visit the shop too. They have some nice books about baking and typical cuisine. And if you don't like cooking (or your German is no good) they have wine and beer also :-)