Andrea & Cristina's place is really good and nice.
It's located close to train station and metro (around 15 minutes walking time) and not too far from city center and main attractions (e.g. around 30 minutes walking time to Colosseum).
Immediate neighborhood is charming and has lots of cafes.
On the downside are a bit steep stairs and 5th floor. Area that is closer to train station looks a bit hostile as well.