We had a very nice stay at Rosa's place. Fantastic location for exploring Paris. We were there for the record-breaking heat wave (105F the day we arrived) and luckily those thick walls keep the heat out for the most part and we were comfortable even without AC. The train noise wasn't an issue for us, I did find that it's slightly more noticeable in the kitchen/living area, so if you have someone who is a lighter sleeper make sure they're in one of the bedrooms. Overall a great spot!