I stayed here for 4 weeks while I was working weekdays near Grand Central. It is a clean modern apartment with new appliances and fixtures and amenities well suited to long stays, notably an en-suite washer/dryer which is a rarity in New York apartments.
The place is situated on a fairly quiet street across from St. Mary’s Park (closed for renovation during my stay January 2020). Also the single bedroom faces onto the back garden so you get very little traffic sound in that room. There is sometimes noise from the upstairs apartment but seldom past 11pm so was never an issue for me getting a peaceful night’s sleep.
St. Mary’s Recreation Center is a 5 minute walk from the apartment. It has a gym and one of the city’s better indoor public pools. If you are a fitness buff and are doing a long stay it might be worth your while to get a membership, $75 gets you 6 months of access to this and all the other city-run recreation centers.
There is quite fast access to Manhattan and Brooklyn via the 4/5/6 subway. Several 6 line stations are within a ten minute walk.
Personally I like the realness of the neighborhood but be aware that South Bronx is among the lowest-income jurisdictions in the USA, so you will see poverty. I walked to and from the subway every day for a month and never had any problems, but I can imagine that some guests without experience of pre-gentrification American urban places might feel uneasy on the streets after dark. Guess you can always use Uber or Lyft if that becomes a issue.
Communication and check-in was straightforward, I felt well taken care of.