I'm a medical student who stayed at Rosemarie's place for 4 months while doing rotations at King's County Hospital. Rosemarie and her husband are excellent hosts! The apartment is pretty much as described. You'll get a bedroom with a queen sized bed, desk, lamp, drawer unit, and closet/armoire. There's a living room area with a tv you can use and some tables to eat/relax. Bathroom is shared amongst renters only, not the hosts, and during my stay I mostly shared it with 1-2 people so it wasn't very busy. This apartment is comfortable and the hosts are very friendly and accommodating.
Additionally, I found that they were constantly working on upgrading the apartment during my stay (not major renovations, just stuff like noticing extra/better caddies in the shower or new appliances in the kitchen to use). The kitchen (and fridge) might be a downside to those who like to cook a lot as it will be shared amongst everyone, including the hosts. You'll have full access to everything, though.
Another downside is that the street noise can be loud at night due to the apartment's close proximity to a busy intersection and multiple hospitals. I slept fine with some earplugs. The flip side is that you'll have excellent access to grocery stores, food, and the like while also being within walking distance of King's County Hospital, Kingsbrook Jewish Hospital, and multiple bus/subway stops. Overall, I had a great stay, and I think this is an ideal place to rent if you're looking for a nice place to just work and study for a month.