We only stayed at the Casa Blanca for one night on our way to Colca canyon. It was quaint and comfortable. The hotel doesn't consist of too many rooms (as far as we could tell), and has a bar and cafe downstairs. Apparently the cafe in the lobby is also quite famous for their smoothies which were delicious. The property is a hotel, tour agency, cafe and bar, all in one!
Our room was a double with bathroom. It was very earthy, but clean, with nice soaps, good heating, and hot water all day. My only complaint is that it was somewhat small (especially the bathroom) but it was fine for a short stay. The bed was comfortable. There was no major noise coming from the cafe when we stayed, and that didn't ever bother us anyway. The staff helped us book our visit to Colca canyon, so it was helpful that they also handled tourism and booking. It was a 15 min walk or so to the Plaza de armas and main shopping area.
Overall, a pleasant stay!