I travelled from Berlin to Brussels on Thursday night. Overall I was satisfied. The coach was tired but clean, the bunks were comfortable (I thought that I'd booked in a six berth compartment but ended up in a five), having an opening window meant that we got ventilation (I've had sleepless nights before in compartments where the aircon wasn't up to the job), several toilets were out of action so I did have to walk a coach and a half before finding one that worked. It arrived at Berlin Hbf an hour late (mercifully as my train from Poland was late too) but seemed to make up time by the Dutch border. In the Netherlands it did have quite an abrupt stop at some point, and the rest of the journey was signal-to-signal (presumably due to lost path) so it arrived in Brussels 39 minutes late. Not too late by sleeper standards, particularly for anything which goes near Germany. I didn't mind the late arrival because it reduced the time festering in Brussels before my Eurostar.
Most importantly I had a good night's sleep, something I haven't had on some of the Nightjets I've taken, nor on a Caledonian Sleeper Mk3 (right at the end of service), never mind the lumpy middle berths in a Romanian couchette (the bunk folds around the headrest wings on those). A youth spent at sea has got me used to a rocking motion and white noise which probably helps. I certainly slept better than I did the following night in my own bed, where the cat kept pestering me.
