An ok experience, however I guess I had wrong expectations. The rooms are small (but that's it in the very city center), Zen rooms don't have a desk for light working, the building next door looks directly into the room, hence one has to pull up curtains which obviously makes the room dark. There were only 2 wall plugs that I could find, paradoxically one on the exact opposite side of the room, making charging phones, tablets etc, a bit challenging.
Beyond that the hotel has a nice vibe, stylishly decorated and I'm sure it probably comes to life more in the summer, as it has a nice lounge at the roof top. The restaurant at the ground floor is ok.
There is no parking at the hotel, obviously since it's in the walking area of the Ljubljana, so if you come with a car it's another ~20€ for overnight parking, just keep that in mind.