My friend and I were in NYC for a visit recently and despite a co-worker saying East Harlem is a not a good place to stay, we went for it. Full disclosure, yes there are undesirable characters close by on Lexington Ave. However, this was never a problem and the ones we spoke to were friendly and funny. Just be smart, problems can happen in any city.
The place itself offered everything we needed, all the kitchen and bathroom amenities one would hope for. The AC is powerful and will cool down the apartment on a hot sunny day. The location is very close to the subway station which is easy to navigate and it's not a far walk to Central Park. Would I stay here again and recommend it to my friends? Yes and already have suggested this place to friends.
As for the owner, I don't have enough characters remaining to say how helpful, knowledgeable and attentive he was. A thousand thanks! Made the stay... pretty much perfect.