Siesta's Hostel is located 7 min away from Ueno Park. A lot of restaurants, bars and shops as well as the famous Ameya Yokocho (a long street with many little shops) are nearby.
Siesta's place is located in a quiet side street. The check-in was very easy. The rooms and facilities are clean and tidy, the common room is spacious and quiet. They have free coffee and tea in the common room, as well as some snacks. The beds are super comfortable and the sleeping room was well heated in the winter.
All in all a great hostel for a very reasonable price. I'd definitely come back for my next trip to Tokyo.