We stayed at B&B Guste for 4 nights in May 2011. We were in the green room which had a private balcony.
Location - quite convenient. 5-10 min walk to the San Giovanni metro station. Right next door to a convenience store - which was very helpful since we packed our lunch some days. Also walking distance to the bus stop and shopping (both high-end and regular).
Cleanliness - The room was very well maintained. There are 2 common baths shared by 3 rooms. The bathrooms are not squeaky clean, but they were not bad enough to be called unclean either.
Reception - We were greeted by Gaga who was very friendly and gave us inputs on how to go around the city.
Amenities - The hotel did not have wifi working when we were there, but we were able to get an unsecured wifi which we used. There is not TV in the room, but there is one in the common room - which we never watched since we were outdoors all day. Breakfast was good - they had fruits, bread, spread, milk, coffee, croissant, pie etc and it was plentiful.
It was great value and I wouldn't hesitate to stay there if we were in the city again.