Jillian's Studio is a functional base from which to connect with NYC Subway (10 Mins on foot) and walk directly to Central Park (20 Mins). It's also in a really authentic neighborhood, with a large Mexican community. The residential architecture and tree-lined streets are real New York at its best. While we were safe at all times, this is definitely an area to display more caution in evenings, however, but traveling around in couples or small groups is certainly no problem.
Be very clear with your host when agreeing check-in time. We confirmed ours pre-flight and then again at JFK upon our arrival (2 hrs before hand). When we arrived on-time, however, we were sorely disappointed at a locked door, and no US cell/mobile coverage to get our host to open up. This eventually ended in the spectacle of one of us staying with the suitcases and the other asking for use of a phone in a local restaurant. This was underwhelming by any standard, but we did get access some 20 minutes after our arrival.
The apartment has all the size and functions you would want to support your stay. The bed is comfortable and the Air-con allows for a livable indoor temperature during hotter days and nights. Do make sure to run the hot water for anything you can do pre-shower (i.e. washing the dishes), however, as it takes a while to get up to the top floor (par for the course with these buildings).
Make sure to compare amenities on arrival with those listed. Host is very good at sorting out any that are missing, and communicates very quickly!