Stayed for one night at Hotel One while attending a two-day congress at De Doelen, Rotterdam : so ideally located.
First of all, the hotel staff was very friendly and helpful. They kept our bags as we arrived quite early, and the right suitcase was in the right room when we came back in the evening.
My colleague and I each had a single room - and the rooms were very small indeed. Having said that, the furniture did have a luxurious feel to it and everything was clean, spotless even, also in the bathroom.

The fresh and new smell of the rooms does not apply to the hallways - they were tired and sombre, in need of a loving hand. You have to go through a lot of doors and take a lot of corners if you have room 27 or 37, which raises some questions about safety in case of a fire. There stairs are quite steep, but there's a small (kinda dodgy) elevator if you want to use that.

There's a restaurant below, but we did not have any noise from there. Can't tell you what it's like as we had dinner somewhere else - breakfast was a minimum. No fancy things, just the basic elements there.

I wouldn't consider this a 4-star hotel though. It's certainly a good quality hotel, with excellent staff, but a 4-star hotel really has those little extra things which make it special. For me, there were too many things on the downside to rate this hotel at more than three stars.

I would never consider this 4 star. The rooms need updating and they are noisy. Don't expect a quiet night (either from outside or the Sumo restaurant underneath). The best thing about this hotel is the location to Centraal Station.

I arrived at the hotel about two hours before check-in time, and I was met by a friendly receptionist who was very helpful. I was offered to leave both of my bags in the reception, and was given good directions of places to see, and a map.

The room was small, but clean. There was a little bit of wear and tear some places, but overall impression was good housekeeping. The sound insulation has room for improvement, but it was to live with. Mattress was soft, the pillow was hard, but there was a big soft pillow in the locker. Also in the locker, a room safe with code lock. Big enough for a notebook and some more small valuables. The bathroom was like the room, small, but clean. Towels and dispenser soap. The free internet access had a ok speed.

Great hotel to stay at if you want a cool place located in downtown Rotterdam. It is great, that is, if you are travelling with friends and you will be getting to bed late anyways. Unfortunately, it is not such a great hotel if you value your sleep. As interesting and charming as the hotel itself is, the walls are paper thin. I could easily hear all conversations coming from the adjoining room. Luckily, I simply talked to the people in the next room and asked them to be quiet -- unluckily I didn't have to open my door to do so.

The staff were friendly.

There is free WiFi access!

The Sushi restaurant downstairs is incredible. But WATCH OUT: water is 2 Euros a glass, and they don't tell you beforehand!