We had a nice stay in Elena's flat. The flat is very well situated, far enough from Manhattan to be less expensive but close enough to be able to easily and quickly reach all the places to visit. The L train station (Grand Street) is literally just outside the flat and takes you to Central NYC in 10 minutes (Union Station). Easy to catch pretty much anywhere. It's also perfectly situated to visit Brooklyn.
We didn't stay in the neighbourhood much but there's a 'supermarket', a 24h deli, a mcdonalds and a few restaurants and bakeries. We didn't have any problems there, it seems pretty safe.
The flat is big and very clean. The room is exactly as pictured: big, clean and functional (big bed for two, bed linens, desk, drawers). We had free access to the living room and kitchen, both clean and well equipped. Elena kindly offered us tea, coffee and cereals. The bathroom is smallish but new and clean. Elena's room was on the other side of the flat, we had our privacy. The bedroom is on the street so there is a bit of noise at night but you get used to it quickly and barely notice it if you're from a big city.
Elena is very easy going. We didn't see her much but she was always available to answer our questions or help us in any way.
Two things to note: the WiFi tend to lag a bit in the room since the router is in Elena's room. When it did, we just moved to the living room. The heating was turning off and on on its own and we couldn't control it. Luckily we had nice weather and didn't miss it much.
All in all, we would totally go back to Elena's if we happen to be in NYC again.