Daniela is great and very sweet and helpfull, I think she's the best host you can wish for.
The area is fine and safe with the J and also the C train closeby. I'm a girl alone and I've not felt unsafe.
The small room is good. I've stayed in there for six weeks and the room as no window, so in the end I kinda missed the fresh air. Also there's a club next door downstairs and you can hear/feel the bass through the floor, but only lightly. It only bothered me a few times, but I also think NYC is a noisy city and it's quite normal.
Big ups: great host, clean, you'll meet nice people, close to airport and Rockaway Beach, close to two trains, laundromat around corner.
Downs: no window in small room, noisy club (bring earplugs).
I really enjoyed my summer at Daniela's! :)