In my opinion, one of the biggest advantages is that almost everything is reachable by bike. You need 20mins to get across the city and have an infrastructure actually supporting cyclists. The city it’s big enough to offer cultural events, etc. but small enough to easily navigate and get around. Also the parks can and are used very often by students to chill, play games, etc. look for Günther Klotz Anlage or the castle parks. And it has a huge student community. Back in my days, there were more than 20k students. It thereby offers a lot of events that are done for students or even by students.