I mean, they're clearly 90s carriages and a bit rattly but perfectly clean and comfortable, as long as you don't mind sharing toilets/bathrooms (1st class sleepers are ensuite).

As for the outward route, Deutsche Bahn seems to be in a right state. Every train late*, and don't trust them to recommend your route or honour your seat reservations. (*Crucially our Berlin change. Arrived 30 mins late, contemplating emergency hotel... but ongoing train mercifully also late)