I was very happy with my stay at Hobo Helsinki. The location is perfect for exploring the center. It's a 5-to-10-minute walk from the central train station and there is a tram stop right around the corner that will take you to the port for a ferry to Tallinn, Estonia.
I was on the 4th-floor facing the street, but the room was the quietest I have ever slept in. I never heard any noise from the street, the hallway, or from adjacent rooms. Was I the only person on that floor?
The breakfast buffet here is amazing! Thy serve delicious hot food - the roasted pork belly was awesome - and cold food options from basic cereals to traditional Finnish foods like whipped blueberry semolina porridge.
I would absolutely stay here again. My only regret was that my room didn't have a comfortable chair to sit in or a table or desk to work at. Maybe the higher priced rooms have those things. But my room and the bathroom were spacious and the shower was great.