We found this hotel through tripadvisor. Everybody here is very positive about the staff, and so are we. On arrival we were given tea and fruit if we wanted, Moon (the owner) gave us a lot of tips about places to go etc.
Downside of this hotel: on every arrival they say the hotel is full and that they can arrange a stay for you in a different hotel (to us they said it was the hotel of Moon's sister called Hanoi Guesthouse) that is as good and the same price as this one. They'll pay for the taxi to the other hotel. Because we heard from other travellers that the other hotel is definitely not as nice as this one, we decided that we did not want to go somewhere else.
Through Moon we booked our trip to Sapa ($125,- pp for train (and pick-up to the station), guide and 2 nights (one in a hotel and one in a guest house). The trip was very nice, Sapa is a very very beautiful place. The hotel (Global Hotel) was very cold though! Had to eat with our jackets on and in the rooms (with a small electric heater) it was still very cold. The view must be amazing, but during out stay it sadly was foggy all the time. In the guest house it was warmer luckily.
When we came back to the Blue Sky Hotel from the Sapa-trip at around 6:30 in the morning, we had to wake up the night guard and he told us that he didn't have a room for us. Before we went on the trip we specifically asked for a room in their hotel and not a different one and they told us that they would keep a room for us. But this time again the staff told us that they didn't have a room for us. After a little hassle we were told one room would become available at 12. But then another couple came back from the trip and the guard told them the same story!
We decided to go somewhere else and are very happy with our decision (Queen Palace Hotel at Hang Bac 116, in the middle of Old Quarter). The beds there are nicer (no springs sticking out), breakfast the same and the owner Tony maybe even more friendly than the staff at the Blue Sky hotel. Through this new hotel we headed out for a trip to Halong Bay and when we came back they kept us the room they had promised! Blue Sky Hotel can learn a thing or to from Tony!
All in all: nice staff, but very very sloppy with their reservations! We would not advise this hotel!