We stayed about 4 days at Hanoi Traveller Hostel.
We wished to stay in the old Hanoi, and we entered randomly in Hanoi Traveller Hostel... But then we stayed on purpose because we felt so well.
We tried 2 bedrooms and all have their advantages: at the backyard, it is very quiet; on the front, the balcony is great to observe Hanoi life. They are all clean and cheap. Some of them need a refreshment which is on the way apparently.
We loved walking around, enjoyed the food and the massages in the spa, just cross the road.