The Blue House was a really great choice for staying in Lisbon. The apartment was spacious, comfortable, and cozy and it's easy walking distance to many great sights.
Everything worked well and was according to the descriptions. Yes, it is a struggle to climb the hill and stairs IF you're bringing heavy bag ;-) BUT it is worth it, because of the nice apartment and the friendly and super helpful staff.
The wall painting is a nice touch and the rooms are very cozy. It was also true that although the street is lively at night, the windows protect against the sound quite a lot. So unless you're a super light sleeper, you should be able to abstract from the sounds.
The day trip we booked for Sintra was really worth it and a great day trip and the staff was always very helpful.
Remember the the office is closed briefly at midday.