We were in an older generation train (the new generation had been scheduled, but then delayed). The shower rotated (and was raised) from the sink. There was a curtain. Seat61 posted a short video linked from the page above, where you can see a glimpse of the bathroom at the end:
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It wasn’t luxurious and the attendant was a bit surly, but I didn’t care as I was so excited to try it. Don’t expect an amenity kit along the lines of international business class. Breakfast was fine but not fine dining by any stretch.
We made the mistake of booking the train for the day after we arrived in Europe, so we were still jet lagged and had some trouble sleeping. But again, I love trains!