This place has a fantastic location! We stayed 4 nights and did the entire city (plus Vatican) all by walking (together with 1 year old!). Everything’s at hand and nearby. The apartment has everything you might need. The street outside is indeed a bit noisy, but I have to say neither us nor the baby cared and slept perfectly.
The only reason for 4 stars is a challenging hot water supply. If you need a hot steamy shower in the morning you might have a bad surprise :) however I think this would be a price to pay for staying in the old building in the middle of Rome city center ;)
Would recommend this place !!