I took an overnight train last fall from Munich to Venice. If I remember right, it was around 110 EUR or so. Overall, it saved me a decent amount of money because it was Oktoberfest in Munich, so my cheap dorm bed in a hostel was running me 60EUR/night and my AirBnB in Venice was around 45EUR/night too. Not to mention, non-stop flights from Munich to Venice I was finding were closer to $150+ in addition to the travel costs to and from the airport.
Long story short, it was fine. - 4 beds per cabin and we had a pastry, juice and coffee served in the morning. I probably got 5 hours or so of sleep, so while I wasn't fully rested, it wasn't horrible. Better than I sleep on planes in Y at least. My only complaint was that they had an intermediate stop an hour or so after we left Munich in Salzburg and let on additional travelers. This woke me up at like 12:30AM and didn't help much with the sleep. I wish they would have arranged the cabins so that you didnt have people coming and going in the middle of the night and instead have everyone from Munich take the first 3 cabins and then everyone from Salzburg take the next 3