Constant noise. It's everywhere and all the time. If you're unlucky visitor who's room facing the street - you're in trouble. I stayed in 102 and during the day (starting from 7:00) there are construction and road works, some heavy equipment movings and what not.
At evening and nights there are lots of loud music from several night clubs and restaurants across the street. People shouting, cars honking...
This hotel has no noise proof at all.
WiFi - probably the worst I've experienced. On the paper, they provide a free WiFi and that is true. But in fact you have to sign in every time you turn on your device or every time you "wake it up" after suspend. Also, if you're connected too much, it keeps bugging you with that sign in nonsense every 30-40 minutes or so.
Effectiveness of the staff. While they're all very friendly and nice, this doesn't always work. The staff at the counter seems to be undermanned, you have to wait in line every time you have even a simple question.
Also, it took them 2 days (or two nights) to get my heating system. I had to complain two times.
There's no ventilation in the bathroom. Also, several items look to be just painted over instead of being cleaned. Who paints a bathroom sink from the inside?
Not enough lights at the room and the dining area.
Location. It's just unbeatable. You have the Stadhuis station just over the corner and Rotterdam Centraal just in 5 minutes walk.
Breakfast. It was all the same every day, but it was good. Many choices an tasty. Sufficient enough to sustain a tourist for several hours.
Price. Somehow I paid for a double room slightly less than they usually charge for a single one.
Room. Spacious enough.
Staff - friendly and nice.